I review the basics and current status of machine learning in particle/nuclear physics, with emphasis on understanding how it works.
The Age of Computation is yet to Come
The theory of classical universal computation was laid down in 1936, was implemented within a decade, became commercial within another decade, and dominated the world’s economy half a century later. This success story relied on the progress in technology. As computers become faster they must become smaller. The history of computer technology has...
The higher-order fluctuations of conserved quantities such as net baryon number are predicted to be sensitive to the non-equilibrium correlation length, $\xi$, and thus serve as indicators of critical behavior. Experimentally, fluctuations of proton and anti-proton numbers have been shown to be reliable proxies for baryons and anti-baryons. In the first Beam Energy Scan (BES-I) at the...
Jets correlated with isolated photons are a promising channel to study jet quenching in heavy-ion collisions, as photons do not interact strongly and therefore constrain the $Q^2$ of the initial hard scattering. The measurement of isolated single photon production constrains NLO pQCD predictions and PDFs, and isolated photon production in Pb-Pb collisions is sensitive to initial geometrical...
Isolated photons and dijets measurements in small collision systems probe the initial state of the collision, providing the opportunity to constrain PDFs, test pQCD predictions, and probe cold nuclear matter effects. In addition, dijet measurements are sensitive to interactions of partons with the medium produced in Pb-Pb collisions that induce modifications in jet properties. Measurements in...
In non-central heavy-ion collisions (HIC), the large initial angular momentum can induce a non-vanishing polarization for hadrons with non-zero spin. The global spin alignment of vector mesons, quantified by the $00^{th}$ element of spin density matrix ($\rho_{00}$), can offer information on the spin-orbital interactions of the QCD medium. Surprisingly large signal of vector meson $\rho_{00}$...
Measurements of high $p_\mathrm{T}$ hadrons produced in hard scattering events offer insight to the modification of jet fragmentation and medium response of the quark-gluon plasma (QGP)
created in ultrarelativistic nucleus-nucleus collisions.
The hard scatter, tagged by an electroweak boson or a jet, fixes initial properties of the showering partons prior to interactions with the QGP. In...
Beams of relativistic heavy ions are accompanied by a large flux of equivalent photons, and thus photon-induced reactions are the dominant interaction mechanism in heavy-ion collisions when the colliding nuclei have transverse separation larger than the nuclear diameter. In these ultra-peripheral collisions (UPCs) the photon can provide a clean probe of the partonic structure of the nucleus...
Polarization and spin-alignment measurements represent an important tool for the understanding of the particle production mechanisms occurring in proton–proton collisions. When considering heavy-ion collisions, quarkonium polarization could also be used to investigate the characteristics of the hot and dense medium (quark-gluon plasma) created at LHC energies. In ALICE, this observable was...
During the evolution of a heavy ion collision, the system passes close to the O(4) critical point. The order parameter that controls the chiral symmetry is the quark condensate $\langle \bar q q \rangle \sim \phi_a $. Due to the non-zero quark mass, there is a crossover (not a second order phase transition) between the high and low temperature phases. In this talk we will introduce the...
Lattice QCD simulations have shown unequivocally that the transition from hadrons to quarks and gluons is a crossover when the baryon chemical potential is zero or small. Many model calculations predict the existence of a critical point at a value of the chemical potential where current lattice simulations are unreliable. We show how to embed a critical point in a smooth background equation...
The physics interpretation of the recent measurements of the spin polarization of Λ hyperons produced in relativistic heavy-ion collisions is discussed. It is suggested that the polarization measured in the Λ rest frame should be projected along the direction of the total angular momentum that is first transformed to the same frame, and only then averaged over Λ’s with different momenta in the...
Over the last decades, many of the available theoretical jet quenching formalisms have been extended to account for the medium’s finite longitudinal extension and expansion. However, only recently a first-principle approach has been developed that allows to study jet evolution in anisotropic media in the dilute limit. In this talk, we show how to extend some of the previous results to the...
Z bosons can be used to constrain the initial energy, direction, and the flavor of the recoiling parton before its interaction with the quark-gluon plasma. By measuring charged particle yields in Z boson events one can study the in-medium modifications of the recoiling parton showers and as well as the soft particles from medium response. The talk will present measurements of the azimuthal...
Recent observations for the spin polarization and alignments in RHIC and LHC have triggered intensive studies for vorticity-induced polarization and spin dynamics in relativistic fluids. We study the important, yet widely overlooked, role of gluons for spin transport with a connection to local parity violation in quark gluon plasmas. We extend the newly developed quantum kinetic theory for...
In the context of the search for the QCD critical point using
non-Gaussian fluctuations, we obtain the evolution equations for
non-Gaussian cumulants within hydrodynamics to leading order of the
systematic expansion in the magnitude of thermal fluctuations. We
develop diagrammatic technique in which the leading order
contributions are given by tree diagrams. We introduce the concept of
...
We report high-statistics measurements of semi-inclusive distributions of charged jets recoiling from high-$E_{\text{T}}$ direct photon ($\gamma_{\text{dir}}$) and $\pi^{0}$ triggers in $p$+$p$ and central Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. In a semi-inclusive approach, event bias is induced solely by the choice of trigger; separately utilizing $\gamma_{\text{dir}}$ and $\pi^{0}$...
Angular correlations present in dijet photoproduction are studied, for the first time, using ultraperipheral lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The second moment of the angular distribution, $\langle \cos(2\Phi) \rangle$, where $\Phi$ is the angle between the vector sum $\vec{Q}_\mathrm{T}$ and the vector difference $\vec{P}_\mathrm{T}$ of the...
By including the recently introduced thermal shear term of the spin polarization vector at local equilibrium we determine longitudinal polarization of Λ hyperons emitted from a hot and rotating hadronic medium using the thermal model with single freeze-out. In our analysis we consider top RHIC energy and use the model parameters which were determined in the previous analyses of particle...
Within the framework of a 3+1D Boltzmann transport approach at fixed $\eta/s$ with the full collision integral, we investigate the existence of far-from equilibrium attractors in momentum moments of the one particle distribution function. We first compare our results for a conformal and non conformal gas for different values of $\eta/s$ and $m$, in order to investigate the role of the equation...
We show that the values of the first three cumulants of the baryon number distribution can be used to calculate the isothermal speed of sound and its logarithmic derivative with respect to the baryon number density. We discuss application of this result to heavy-ion collision experiments and address possible challenges, including effects due to baryon number conservation, differences between...
Experimentalists and theorists are pushing towards studying large radius jets in heavy ion collisions in an endeavour to decode signs of induced radiation and medium response with increasing precision. However, even at mid-rapidity, jets are not entirely composed of final state emissions, but contain a varying amount of initial state radiation. This contribution is small for small radius...
Charged particles in heavy-ion collisions have various production mechanisms, such as thermal and associated production, and the importance of each changes with the collision energy. Studying the yields of charged particles provides a way to investigate the properties of the produced QCD matter in heavy-ion collisions and the various production mechanisms. The RHIC Beam Energy Scan (BES)...
In this work, we introduce both gluon and quark degrees of freedom for describing the partonic cascades inside the medium. We present numerical solutions for the set of coupled evolution equations with splitting kernels calculated for the static, exponential and Bjorken expanding media to arrive at medium-modified parton spectra for quark and gluon initiated jets respectively. We discuss novel...
We establish the existence of a far-from-equilibrium attractor in weakly-coupled gauge theory undergoing one-dimensional Bjorken expansion. We demonstrate that the resulting far-from-equilibrium evolution is insensitive to certain features of the initial condition, including both the initial momentum-space anisotropy and initial occupancy. We find that this insensitivity extends beyond the...
The measurements of spin polarization of particles emitted in heavy-ion collisions has opened the possibility for new phenomenological investigations of spin physics in relativistic fluids. The theoretical predictions of global polarization are in agreement with the data, but consistent discrepancies stand out for the local polarization. In this talk, I will show that the covariant theory of...
We explore jet-medium interactions at various scales in high-energy heavy-ion collisions using JETSCAPE 3, a publicly available software framework for Monte Carlo event generators. In jet shower evolution, the virtuality and energy of each jet parton vary considerably. Thus, in high-energy heavy-ion collisions, jets can be used as dynamical probes to investigate the jet-medium interaction at...
The relativistic generalization of the relaxation time approximation proposed by Anderson and Witting [1] is widely used in several fields of physics and, in particular, in the study of the hydrodynamization of the matter produced in ultrarelativistic heavy ion collisions. We demonstrate that the approximation proposed by Anderson and Witting contains basic flaws, not being consistent with...
Even though QGP, when looked at on length scales of order the inverse of its temperature, is best described as a strongly coupled liquid, when it is observed at sufficiently short length scales or probed at sufficiently high exchanged-momentum, asymptotic freedom predicts the presence of quark-like and gluon-like quasi-particles. High energy partons (e.g. those in jet showers) traversing the...
The local Lambda polarization puzzle associated with the model calculations by thermal vorticity has attracted lots of attention in heavy ion community [1].
In addition to the widely studied thermal vorticity effect, we identify an undiscovered contribution from the fluid shear [2]. We obtain the explicit expression for shear-induced polarization (SIP) from quantum kinetic equation and...
Measurements of anisotropic flow in heavy-ion collisions are key to extract properties of the quark-gluon plasma (QGP). The combination of different flow harmonics relative to the participant and spectator planes provides a unique insight into the initial conditions and the space-time evolution of such collisions. In particular, the spectator plane provides novel information about the...
A new approach is presented to explore the singularity structure of lattice QCD in the complex chemical potential and fugacity plane [1, 2, 3]. Our method can be seen as a combination of the Taylor expansion and analytic continuation approaches. Its novelty lies in using rational (Padé) approximants for studying Lee Yang edge singularities, which provide valuable insights to the occur- rence...
Crossover Scenario
If there were a first-order phase transition, some signatures could be expected, but the most challenging is an experimental confirmation of realistic crossover scenario. It is already known from the NS observations / pQCD calculations that a crossover transition to quark matter is likely to occur around 3-5 times normal nuclear density, where a slope parameter on the...
It is well established that hard partons lose energy as they traverse the quark-gluon plasma (QGP). However, while there has been significant work to describe the mechanism by which this occurs, the relative contributions of the microscopic processes have yet to be constrained experimentally. One way to address this question is to exploit the theoretically derived relationship between the...
RHIC's capability to perform relativistic collisions of various ion species provides a unique opportunity to explore and constrain neutron skin thickness and deformation parameters of nuclei.
The study of neutron skin thickness $\Delta r_{np}$ of nuclei can help us directly infer nuclear symmetry energy. Such information is of critical importance to the equation of state of dense...
Fluctuations of conserved charges in a grand canonical ensemble
can be computed on the lattice and, thus, provide theoretical
input for freeze-out phenomenology. Electric charge fluctuations
and the corresponding higher order correlators are extremely
difficult, suffering form the most severe lattice artefacts.
We present new simulation data with a novel discretization where
these...
It has been shown that high-energy partons lose energy when traversing the hot, dense medium produced in heavy-ion collisions. However, the mechanism of the energy loss, including its dependence on the path-length of the shower in the medium and sensitivity to the jet substructure, is not fully understood. This talk presents a new measurement of single jet yields as a function of the azimuthal...
I discuss the recent progress in state-of-the art perturbative QCD calculations of the equation of state at large chemical potential. I describe why these calculations that are reliable at asymptotically high densities constrain the equation of state at neutron star densities, and describe how the theoretical calculations can be confronted with multimessenger observations to empirically...
Jet-medium interactions in the Quark-Gluon Plasma can receive large non-perturbative infrared contributions. These contributions affect transverse jet momentum broadening and jet quenching. Both are influenced by the modified in-medium dispersion of jets encoded in their asymptotic mass.
An IR-safe computation of the latter requires subtracting the unphysical UV limit of electrostatic QCD...
In this talk, we analyze the recent astrophysical constraints in the context of a hadronic equation of state (EoS), in which the baryonic matter is subject to chiral symmetry restoration. We show that it is possible to reconcile the modern constraints on the neutron star (NS) radius and tidal deformability (TD). We find that the softening of the EoS (required by the TD constraint) followed by...
Jet quenching is a well-established signature of quark-gluon plasma formation in heavy ion collisions. Studies of the transverse momentum balance of back-to-back jets, as well as medium-induced modifications to jet shapes and fragmentation functions, provide important experimental constraints on quark-gluon plasma properties. Using a large sample of dijet events from 5.02 TeV PbPb and pp...
The far-from-equilibrium non-abelian plasma is created in the early stage of heavy-ion collision. The “bottom-up” mechanism is the well-studied phenomenological description of its approaching to thermal equilibrium, but has been restricted to leading order coupling within kinetic theory calculation. In our recent work, we provide a next-to-leading-order (NLO) weak-coupling description of the...
We employ an effective kinetic description to study the space-time dynamics and development of transverse flow of small and large collision systems. By combining analytical insights in the few interactions limit with numerical simulations at higher opacity, we are able to describe the development of transverse flow from very small to very large opacities, realised in small and large collision...
The upcoming run of oxygen-oxygen (OO) collisions at the LHC offers unique experimental and theoretical opportunities to address the long standing question of high-momentum rescattering (jet quenching) in small collision systems. We have demonstrated previously that even small energy loss effect can be observed in nuclear modification factor thanks to high precision pQCD baseline calculations...
Given the lack of empirical evidence of weakly interacting dark matter, it is reasonable to look to other candidates such as a confining dark sector with a similar number of particles as the standard model. Twin Higgs mirror matter is one such model that is a twin of the standard model with particles masses 3-6 times heavier than the standard model that solves the hierarchy problem. This...
Dense QCD matter can exhibit spatially modulated regimes. They can be characterized by particles with a moat spectrum, where the minimum of the energy is over a sphere at nonzero momentum. Such a moat regime can either be a precursor for the formation inhomogeneous condensates, or signal a quantum pion liquid. We discuss the underlying physics of the moat regime based on studies in low-energy...
Determining the multi dimensional structure of protons and nuclei at high energy is one central goal of the future Electron-Ion Collider. This fundamental information is a crucial input for models describing the initial state of heavy ion collisions. In particular the event-by-event fluctuating proton geometry should have a strong effect on the flow and multiplicity distribution in high...
While a variety of jet substructure measurements have been performed in heavy-ion collisions, a unified understanding of how the QGP affects the angular and momentum structure of jets remains an open question. One of the prominent puzzles is that measurements indicate no significant modification of the jet mass in heavy-ion collisions relative to proton-proton collisions, but significant...
The strong interaction among stable and unstable hadrons is a fundamental question in nuclear physics and a key ingredient for the description of the equation of state and the understanding of the structure of dense stellar objects such as neutron stars. Traditional measurements, including scattering and hypernuclei experiments, are insufficient to provide stringent constraints to the...
We propose a new model for a homogeneous description of hadron-hadron, hadron-nucleus and nucleus-nucleus collisions, the Gluon Exchange Model (GEM). While technically our model can be regarded as a generalization of the Dual Parton Model by Capella and Tran Thanh Van, it is fundamentally based on the number of exchanged color octets (gluons) and significantly extends the Fock space of states...
In Bayesian analyses of heavy ion collisions up to now one usually uses the TRENTo prescription for the initial state, followed by a free streaming initial stage. In this work, we extend this picture in two ways. Firstly, we generalize the TRENTo formula so that it is able to describe binary scaling. This introduces a parameter which we subsequently use to determine whether binary scaling is...
We outline the role that an early deconfinement phase transition from normal nuclear matter to a color superconducting quark-gluon plasma phase plays for the phenomenology of supernova explosions and binary neutron star mergers. To this end we extend the compact star equation of state (EoS) from vanishing to moderately high temperatures that become accessible in the BM(a)N and MPD experiments...
High energy partons are well established to lose energy when traversing the hot and dense medium produced in heavy-ion collisions. This results in a modification to the transverse momentum distributions of jets, producing a phenomenon known as jet quenching. It has been previously established in Pb+Pb collisions at $\sqrt{s_\textrm{NN}}~=~2.76$~TeV that jet quenching results in significant...
Jet-induced medium response carries the information for the properties of quark gluon plasma produced in high-energy heavy-ion collision. Diffusion wake as an unambiguous part of the medium response will lead to a depletion of soft hadrons in the opposite direction of the jet propagation. New experimental data on Z-hadron correlation in Pb+Pb collisions at the Large Hadron Collider show,...
NA61/SHINE is a fixed target experiment at the CERN Super Proton Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and to study the properties of the onset of deconfinement. In order to reach these goals, a study of hadron production properties is performed in nucleus-nucleus, proton-proton and proton-nucleus interactions as a...
Using the second law of local thermodynamics and the first-order Palatini formalism, we formulate relativistic spin hydrodynamics for quantum field theories with Dirac fermions, such as QED and QCD, in a torsionful curved background. We work in a regime where spin density, which is assumed to relax much slower than other non-hydrodynamic modes, is treated as an independent degree of freedom in...
The STAR Collaboration has successfully completed the upgrade of the forward detector system located between 2.5 $< \eta <$ 4.0. This upgrade comprises a Forward Calorimeter System, which contains an Electromagnetic Calorimeter and Hadronic Calorimeter; and a Forward Tracking System which consists of a Forward Silicon Tracker and Forward small-strip Thin Gap Chambers. The forward detector...
In this talk we extend the novel expansion scheme introduced in [1] to explore the impact of a strange and electric charge chemical potential. We focus on the equation of state along the strangness neutral line, which allows us to match conditions in heavy ion collision experiments. We are also able to extrapolate different thermodynamic quantities to values of the strangeness and electric...
The LHCb experiment has recently undergone a series of major upgrades: the entire tracking system has been replaced with higher-granularity sensors, the readout electronics have been upgraded, and all hardware triggers have been removed in favor of a new state-of-the-art streaming readout system. In addition, the gaseous target SMOG system has been upgraded with a dedicated storage cell to...
Observations of strong azimuthal anisotropies ($v_n$)-- and their agreement with some hydrodynamic calculations-- in p+A collisions at RHIC and LHC have led to the suggestion that such collisions produce the smallest droplets of QGP. This hypothesis may be tested from a different angle through hyperon polarization measurements. In particular, central p+A collisions may naturally produce an...
Compared to the earlier calculation of the equation of state of QCD with physical light and strange quark masses, performed in 2017, the HotQCD collaboration has accumulated an order of magnitude larger statistics for up to 8th order cumulants on lattices with temporal extent Nt=8 and 12 and added results for Nt=16 that were not available previously. We use these high statistics results on...
The ultra-peripheral collisions (UPC) of relativistic heavy ion beams lead to a diverse set of photon-nucleus interactions.
The measurements of particles and their interaction produced in photo-nuclear reactions can shed light on the QCD dynamics of novel, extremely asymmetric colliding systems, with energies between those available at RHIC and the LHC.
Understanding the hadronic...
Suppression of charmonia is one of the most distinctive signatures of Quark-Gluon Plasma (QGP) in heavy-ion collisions. Suppression can also take place in hadron-nucleus collisions due to cold nuclear matter (CNM) effects where the presence of QGP is not expected. The hadron-nucleus collisions are therefore important as they help to disentangle the effects of the QGP from those due to CNM....
Over the last years, evidence of collective behavior has been observed in high-multiplicity collisions of small systems, however, its origin is not yet understood. In this talk, we will present the first measurement of ultra-long-range azimuthal angle correlations of identified particles in small collision systems by using forward detectors of ALICE, which allows the largest pseudorapidity...
One of the central goals in QCD with non-vanishing conserved charge densities is to find evidence
for the existence of the so-called critical end point (CEP) in the QCD phase diagram. Lattice QCD
calculations at smaller than physical quark masses, combined with our model based understanding of
the QCD phase diagram, suggest that this critical point, if it exists, needs to be searched for...
After 9 years of successful data-taking in proton-proton and heavy ion collisions at a variety of energies, the ATLAS detector started in 2018 the preparations for an ambitious physics project, aiming the exploration of very rare processes and extreme phase spaces, an endeavor that will require a substantial increase in the amount of data to be taken. To accomplish this purpose, a...
In this contribution, the final measurements of the centrality dependence of $R_{\rm AA}$ of non-prompt $\mathrm{D}^0$ and electrons from beauty hadron decays in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV will be presented. These measurements provide important constraints to the in-medium mass-dependent energy loss and hadronization of the beauty quark. The integrated non-prompt...
The azimuthal anisotropies observed in small systems can originate from the final state response to the initial geometry as well as from initial momentum anisotropies. Recently it has been proposed that the correlation between the flow coefficient $v_{2}^2$ and the mean $p_\mathrm{T}$ carries information on the origin of flow in small collision systems by showing a characteristic sign change...
We present a novel approach to nonperturbatively estimate the heavy quark momentum diffusion coefficient, which is a key input for the theoretical description of heavy quarkonium production in heavy ion collisions, and is important for the understanding of the elliptic flow and nuclear suppression factor of heavy flavor hadrons. In the heavy quark limit, this coefficient is encoded in the...
The sPHENIX detector at the BNL Relativistic Heavy Ion Collider (RHIC) is currently under construction and on schedule for first data in early 2023. Built around the excellent BaBar superconducting solenoid, the central detector consists of a silicon pixel vertexer adapted from the ALICE ITS design, a silicon strip detector with single event timing resolution, a compact TPC, novel EM...
The jet transport coefficient $\hat{q}$ is the leading coefficient that characterizes the transverse broadening of the hard parton traversing QGP. The transverse kicks received from the medium changes the off-shellness of the hard parton, which leads to enhancement in the gluon emissions. Since the transverse broadening is the dominant mechanism responsible for the suppression of the...
Evidence for the production of top quarks in heavy ion collisions is reported in a data sample of lead-lead collisions recorded in 2018 by the CMS experiment at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV, corresponding to an integrated luminosity of $1.7\pm0.1\,\mathrm{nb}^{-1}$. Top quark pair ($\mathrm{t\bar{t}}$) production is measured in events with...
The experimental observations of anisotropic flows in proton-proton and
proton-nucleus collisions at RHIC and LHC energies has stimulated a big
interest in these small systems as a new study area for the formation and
evolution of the quark-gluon plasma. We investigate the effects of
non-equilibrium dynamics in such systems by comparing a microscopic
nonequilibrium transport approach, the...
The Compressed Baryonic Matter (CBM) experiment is one of the major scientific pillars of the Facility for Antiproton and Ion Research (FAIR), which is expected to become operational in 2025-26. The goal of CBM is to explore the QCD phase diagram in the region of high baryon densities using nucleus-nucleus collisions in the energy range \sqrt{s_{NN}} = 2.9 - 4.9 GeV. CBM will be utilizing peak...
The Multi-Purpose Detector (MPD) is the first experiment at the
NICA Collider, which is in construction at the Joint Institute for
Nuclear Research in Dubna. During initial stage of operation the
complex
will study collisions of heavy ions in for sqrt(s_NN) of 4-11 GeV,
with Bi+Bi collisions at 9.2 GeV, in particular planned for first run.
It is expected that an excited QCD matter with...
In this talk I shall review how the S-matrix formalism can be applied to study the thermal properties of interacting hadrons.
The central idea of this approach is to compute an effective density of state from the scattering phase shifts. As the phase shifts encode a wealth of information about the hadronic interactions, the method can robustly handle many dynamical structures, e.g....
Small collision systems exhibit features that are characteristic of collective flow, a hallmark of QGP formation. However, jet quenching in small systems has not yet been observed, and quantifying or setting limits on the magnitude of jet quenching in small systems is a key element in understanding the limits of QGP formation. In this talk we present a search for jet quenching effects in pp...
We make predictions for rapidity densities of beauty hadrons produced in Pb-Pb collisions at LHC energy. The approach follows that outlined for charm in JHEP 07 (2021) 035, with the canonical suppression as an important ingredient. The hadronic mass spectrum is taken from PDG 2020, with 48 b mesons and 46 b baryons in total. As further input we use the measured cross section for...
Azimuthal angle ($\Delta\phi$) and transverse momentum ($p_\mathrm{T}$) correlations of isolated photons and associated jets, which are sensitive to medium induced parton momentum broadening, are reported for the first time with the latest high statistics pp and PbPb data recorded with the CMS detector at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV. The fully corrected photon+jet azimuthal...
The early production of heavy-flavour partons makes them an excellent probe of the dynamical evolution of QCD systems. Jets tagged by the presence of a heavy-flavour hadron give access to the kinematics of the heavy partons, and along with correlation measurements involving heavy-flavour hadrons allow for comparisons of their production, propagation, and fragmentation across different systems....
We present the measurement of two-particle correlations in hadronic $e^+e^-$ collisions data collected by the Belle detector at KEKB. The clean $e^+e^-$ collision system is conducive for the unambiguous investigation of the azimuthal anisotropy of final-state charged particles found in various heavy ion and proton-proton collisions. Following up on the first examination in $e^+e^-$...
The production mechanism of deuterons, which have a binding energy of 2.2 MeV, is a topic of current interest in high energy heavy-ion collisions, where the system undergoes kinetic freeze-out at temperatures around 100 MeV. Two possible scenarios include (a) statistical thermal process and (b) coalescence of nucleons. Cumulants of deuteron number distributions and proton-deuteron correlations...
Transverse momentum broadening and energy loss of a propagating parton are dictated by the space-time profile of the jet transport coefficient $\hat{q}$ in a dense QCD medium. The spatial gradient of $\hat{q}$ perpendicular to the propagation direction can lead to a drift and asymmetry in parton transverse momentum distribution. Such an asymmetry depends on both the spatial position along the...
Exploring the strong interaction among hadrons, the ALICE Collaboration has for the first time extended the experimental measurements from two- to three-body interactions. These measurements provide unique information on many aspects of strongly-coupled systems, like the genuine three-body interaction, the formation of light nuclei and the search for exotic bound states. Among those, many-body...
The first measurement of $anti-k_{T}$ jets and two-particle angular correlations of charged particles emitted in high energy $e^+e^−$ annihilation is presented. The archived data at a center-of-mass energy of 91-209 GeV were collected with the ALEPH detector at LEP between 1992 and 2000.
At 91 GeV, no significant long-range correlation was observed in either the lab coordinate analysis or...
The jet quenching phenomenon, one of the signatures of the quark-gluon plasma, is well established through experimental measurements at RHIC and LHC. However, the details of the expected dependence of jet-medium interactions on the flavor of the parton initiating the shower are not yet settled. This talk presents the first b jet shapes measurements from 5 TeV PbPb and pp collisions collected...
Quark number susceptibilities as computed in lattice QCD are commonly believed to provide insights into the microscopic structure of QCD matter, in particular its degrees of freedom. We generalize a previously constructed partonic $T$-matrix approach to finite chemical potential to calculate various susceptibilities, in particular for configurations containing a heavy charm quark. At vanishing...
A valuable tool used in the search for QCD's critical point is the computation of cumulants of conserved charge. Near this point, it is expected a sharp increase of this quantity due to divergence of correlation lengths. This calculation requires high statistics, which poses a challenge to hydrodynamics simulations, which tends to be computationally expensive. The issue can be ameliorated by...
The creation of fluid-like quark-gluon plasma in small collision systems has been investigated via elliptical azimuthal anisotropy of emitted particles in these interactions. A novel search for QCD collective effects in hard probes is presented using high-$p_\mathrm{T}$ jets in 13 TeV pp collisions at CMS. Studies of short- and long-range azimuthal correlations inside a jet produced with very...
The suppression of the $J/\psi$ nuclear modification factor has been seen as a trademark signature of final state effects in large collision systems for decades. In small systems, deviations of the nuclear modification from unity had been attributed to cold nuclear matter effects until the observation of strong differential suppression of the $\psi(2S)$ state in $p/d$+A collisions, which...
In this contribution, the similarity between small and large collision systems will be further explored using the underlying event (UE) charged-particle density, $N_{\rm T}$ and the self-normalized version, $R_{\rm T}$. By selecting on $N_{\rm T}/R_{\rm T}$ and topological region, different microscopic processes contributing to the inclusive production can be isolated.
Final measurements of...
Measurements of quarkonia and open-heavy flavor in hadronic collisions provide a unique testing ground for understanding quantum chromodynamics (QCD). Although recently there was significant progress, our understanding of hadronic collisions has been challenged by the observation in high-multiplicity proton-proton (pp) collisions of intriguing effects, such as collective phenomena.
The...
We present a dynamical description of (anti)proton number cumulants and correlation functions in heavy-ion collisions by utilizing hydrodynamics simulations [1]. The cumulants are calculated via an appropriately extended Cooper-Frye procedure describing particlization of an interacting hadron resonance gas [2] while the effects of global baryon number conservation are taken into account using...
Jets have become a prominent tool for studying properties of the quark-gluon plasma through observations of in-medium modifications of parton showers and energy loss patterns in heavy-ion collisions. These effects, termed jet quenching, were expected to depend on the color-charge and/or flavor of the parton initiating the shower. The jet charge observable, defined as the momentum-weighted sum...
The JETSCAPE Collaboration reports a new determination of jet transport coefficients in the
Quark-Gluon Plasma, using both reconstructed jet and hadron data measured at RHIC and the
LHC. The JETSCAPE framework incorporates detailed modeling of the dynamical evolution of
the QGP; a multi-stage theoretical approach to in-medium jet evolution and medium response;
and Bayesian inference for...
The observation of collectivity in small hadronic collisions raises the question whether the tiny droplet of quark gluon plasma can form in systems with size significantly smaller than nucleus-nucleus collisions. Dynamics and hadronization of heavy flavor quarks in small-system collisions provide a powerful tool to address the origin of observed collective phenomena because of their early...
The elliptic flow harmonic $v_{2}\{2k\}$ is determined using Q-cumulants of different orders, with $k=1,...,5$, for 5.02 TeV PbPb collisions. The results were obtained using data from the CMS experiment at the LHC. The $v_{2}\{2k\}$ values show an ordering, with $v_{2}\{2\} > v_{2}\{4\} > \approx v_{2}\{6\} > \approx v_{2}\{8\} > \approx v_{2}\{10\}$. The hydrodynamics behavior of the medium...
In the last few years, several frameworks have achieved the evaluation of the medium-induced gluon radiation spectrum (or rate) with all-order resummation of multiple scatterings for static media. However, conceptual and computational issues arise when embedding approaches including multiple scatterings into dynamic plasmas. In this talk, we will show several paths to overcome these...
The medium modification to particle spectra and the origin of collectivity in small collision systems are widely debated topics in our community.
To address these open questions we propose the study of particle production and collectivity for varying system sizes, presented in decreasing order (Au+Au $>$ Ru+Ru/Zr+Zr $>$ $^{3}$He+Au $>$ d+Au $>$ p+Au $>$ p+p $>$ $\gamma$+Au), available at...
The f$_0$(980) resonance was observed several years ago in $\pi\pi$ scattering experiments. Despite a long history of experimental and theoretical studies, the nature of this short-lived resonance is far from being understood and there is no agreement about its quark structure. According to different models, it has been associated with a meson, considered as a tetraquark, or as a KK molecule....
With current and future heavy-ion experiments focusing on understanding the baryon-rich QCD (Quantum Chromodynamic) matter produced at low collisional energies, first-principle knowledge of the equation of state in such regions is essential for analyzing experimental data in terms of transport simulations and to constrain effective models of QCD.
We construct a novel equation of state (EoS)...
In heavy-ion collisions at relativistic energies, a hot and dense medium called quark-gluon plasma (QGP) is created. Intriguingly, the collective motion of produced particles, which is thought to be a strong evidence of the formation of QGP, is also seen in small systems like pp and p–Pb collisions. Such a study can be done in the ALICE experiment at the LHC via long-range two-particle...
Based on a holographic far-from-equilibrium calculation of the Chiral Magnetic Effect (CME) in an expanding quark-gluon plasma, we study collisions at various energies. We compute the time evolution of the CME current in the presence of a time-dependent axial charge density and subject to a time-dependent magnetic field. The plasma expansion leads to a dilution and eventual annihilation of the...
The large data sample of high-multiplicity pp collisions collected by ALICE allows for the precise measurement of the size of source producing primary hadrons, opening the doors to a study of the interaction of different hadron species using femtoscopy techniques. In this contribution, the momentum correlation between (anti)protons and (anti)deuterons measured in pp collisions at $\sqrt{s} =...
The study of nuclear matter over a wide range of collision energy is provided by the RHIC Beam Energy Scan (BES). One focus of the program, namely to locate the critical point (CP) in the QCD phase diagram, is closely tied to the measurement of kurtosis in net-proton multiplicity distribution as a function of $\sqrt{s_{NN}}$.
Previous results from BES-I obtained with $3.1 \sigma$ significance...
The hydrodynamic modeling of the quark-gluon plasma (QGP) permits us today not only to perform quantitative extractions of the transport properties of the QGP, but also to strongly constrain its initial condition. A growing body of experimental evidence shows that the QGP initial condition is strongly impacted by the shape and radial structure of the colliding nuclei. We discuss the exciting...
The yields of light flavour hadrons and light (anti-)nuclei including (anti-)hypernuclei have been measured by the ALICE collaboration at LHC/CERN at various multiplicity bins in proton-proton, proton-lead and lead-lead collisions. It is observed that the strangeness and (anti-)nuclei production increase non-linearly with charged-particle multiplicity (dNch/dy) and is independent of the...
Recently, STAR reported the isobar (${^{96}_{44}\text{Ru}}+{^{96}_{44}\text{Ru}}$, ${^{96}_{40}\text{Zr}}+{^{96}_{40}\text{Zr}}$) results for chiral magnetic effect (CME) search [1]. The Ru+Ru to Zr+Zr ratio of the CME-sensitive observable $\Delta\gamma$, normalized by elliptic anisotropy ($v_{2}$), is close to the inverse multiplicity ($N$) ratio. In other words, the ratio of the...
The underlying event (UE) has been studied in ALICE for pp collisions at $\sqrt{s}$ =5.02 TeV. The average number density and the average total transverse momentum ($p_{\rm T}$) are studied in the near, away and transverse regions as a function of the leading particle $p_{\rm T}$. Results at 5.02 TeV show qualitatively the same behavior as observed at different energies.
For the first time...
Precision measurements of jet substructure are used as a probe of fundamental QCD processes. The primary Lund jet plane density is a two-dimensional visual representation of the radiation off the primary emitter within the jet that can be used to isolate different regions of the QCD phase space. We present a new measurement with the ALICE detector of the primary Lund plane density for...
We point out that the variance of net-baryon distribution normalized by the Skellam distribution baseline, $\kappa_2[B−B¯]/⟨B+B¯⟩$, is sensitive to the possible modification of (anti)baryon yields due to BB¯ annihilation in the hadronic phase. The corresponding measurements can thus place stringent limits on the magnitude of the BB¯ annihilation and its inverse reaction. We perform Monte Carlo...
It is frequently supposed that quark-gluon plasma created in heavy-ion collisions undergoes free streaming at early times. We examine this issue based on the assumption that a universal attractor dominates the dynamics already at the earliest stages, which offers a way to connect the initial state with the start of the hydrodynamic expansion in an approximate but conceptually transparent...
Deep Learning methods are a popular tool for efficient and fast data analysis in high energy/ nuclear physics experiments. The upcoming Compressed Baryonic Matter (CBM) experiment will study nuclear-nuclear collisions in the range of 10- 40 AGeV at an unprecedented event rate of up to 10MHz, creating about 1TB/s of raw data. In order to run the experiment to its full potential, novel methods...
The search for the chiral magnetic effect (CME) in isobaric collisions of Ru+Ru and Zr+Zr at RHIC was motivated by the assumed similarity of the backgrounds (e.g., $v_n$, $N_{\rm chg}$) for the two isobars. The effects of nuclear structure differences and deformation can lead to essential differences in the backgrounds for the two isobars. Here, we use a quark Glauber model, validated in...
Short-lived resonances can probe strongly interacting matter produced in high-energy heavy ion collisions. K$^{*}(892)^{\pm}$ resonance is particularly interesting because of its very short lifetime (∼ 4 fm/c), comparable to the one of the hadronic phase. Therefore, it may be sensitive to the competing rescattering and regeneration mechanisms which modify the particle’s momentum distributions...
Jets are algorithmic proxies of hard scattered quarks/gluons created in collisions of high energy particles. In the last few years, there has seen an explosion of jet substructure results from all experiments derived from exploiting clustering algorithms. Jet quenching via parton energy loss in heavy ion collisions is an established probe for exploring the properties of the quark-gluon plasma....
The azimuthal anisotropy of parton energy loss in non-central heavy-ion collisions can lead to jet anisotropy which in turn can provide insight into the path-length dependence of jet quenching. Jet anisotropy flow in this study is investigated within the Linear Boltzmann Transport model, in which the dynamical evolution of the QGP is simulated within the CLVisc hydrodynamic model with fully...
Heavy quarkonia are important probes of the matter created in heavy ion-collisions. The complex
heavy-quark potential is an essential ingredient of dynamical models of quarkonium production in
heavy-ion collisions, e.g. in models based on open quantum system approach.
We calculate the complex heavy-quark potential in (2+1)-flavor QCD with physical quark masses on
the lattice using...
Recently, many results suggesting the production of Quark-Gluon Plasma (QGP) in high multiplicity events in small collision systems have been presented. These results were reported with surprise and have been a topic of intense discussion.
The purpose of the analysis presented in this talk is to look for the possibility of QGP formation in small collision systems through the measurement of...
The measurement of neutral mesons in pp collisions allows a test of perturbative QCD calculations and represents an important baseline for heavy-ion studies. Neutral mesons are reconstructed in ALICE with multiple methods in a very wide range of transverse momenta and thus impose restrictions on the parton distribution functions and fragmentation functions over a wide kinematic region....
Anisotropic flow of produced hadrons, in particular of multi-strange hyperons, is an important observable for understanding the dynamics and properties of the QCD matter created in heavy-ion collisions at high net baryon densities. The performance of the Compressed Baryonic Matter (CBM) experiment at FAIR is presented for anisotropic flow measurement relative to the projectile spectator plane...
The ALICE experiment is dedicated to investigating a hot and dense deconfined state of matter created in heavy-ion collisions. Complementary measurements in smaller collision systems have shown signs of collectivity emerging even in simple hadronic collisions. Particle production at the LHC is driven by a complex interplay of soft and hard QCD processes. It is still challenging for modern...
Exclusive vector meson production is a powerful process to probe the small Bjorken-$x$ structure of protons and nuclei, as such processes are especially sensitive to gluonic structure and also provide access to the spatial distribution of small-$x$ gluons in nuclei. A powerful theoretical framework to study vector meson production at high energy, and to describe the initial condition of...
Understanding the phase diagram of QCD by measuring fluctuations of conserved charges in heavy-ion collision is one of the main goals of the beam energy scan program at RHIC. For a precise measurement of the cumulants it is necessary to grasp the role of charge conservation in heavy-ion collision measurements. Within this work, we calculate the role of hadronic interactions and momentum cuts...
The search for experimental signatures of the critical point (CP) of strongly interacting matter is one of the main objectives of the NA61/SHINE experiment at CERN SPS. In the course of the experiment, a beam momentum (13A – 150A GeV/$c$) and system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb) scan is performed. Local proton density fluctuations in transverse space represent an order parameter...
We tried to locate the initial jet production positions in QGP, using the jet energy loss along the path length direction, the asymmetry perpendicular to the path length from gradient-tomography and the energy momentum distribution inside the jet with deep learning. These machine learning assisted Jet tomography help to locate the jet production positions with reasonable precision that helps...
Hadronic resonances are effective tools for studying the hadronic phase in ultra-relativistic heavy-ion collisions. In fact, their lifetime is comparable to the hadronic phase and resonances are sensitive to the hadronic phase effects such as re-scattering and regeneration processes which might affect the resonance yields and shape of the transverse momentum spectra. $\Lambda(1520)$ has a...
Jet observables, including jet fragmentation transverse momentum $j_{\rm T}$, parallel momentum $p_{\left|\right|}$, jet fragmentation function $\xi$ and jet constituent transverse momentum $p_{\rm T, track}$ distributions, have been investigated in p $+$ p and p $+$ Pb collisions at $\sqrt{s_{\rm NN}} = 5.02~{\rm TeV}$ via a multiphase transport model (AMPT) [1,2] with new hadronization model...
Recent relativistic heavy-ion collision experiments have found evidence for the generation of strong magnetic field and global angular momentum. The numerical simulation of evolution of the QCD medium is based on either magnetohydrodynamics or spin-hydrodynamics for calculation of observables pertaining to magnetic field or global angular momentum, respectively. However, these two effects are...
To probe the Chiral Magnetic Effect (CME) in heavy-ion collisions, a new technique, Sliding Dumbbell Method (SDM) [1] is developed to search for the back-to-back charge separation on event-by-event basis. The SDM helps in selecting the events corresponding to different charge separations ($f_{DbCS}$). The charge separation distributions for each collision centrality is divided into 10...
Event-by-event fluctuations of the mean transverse momentum, $\langle p_{\rm{T} }\rangle$, of charged particles produced in Pb--Pb and Xe--Xe collisions at $\sqrt {s_{\rm{NN} }}= 5.02 $ TeV and $\sqrt {s_{\rm{NN} }}= 5.44$ TeV, respectively, and pp collisions at $\sqrt s = 5.02 $ TeV are studied as a function of the charged-particle multiplicity using the ALICE detector at the LHC....
Hydrodynamics is an effective theory for the description of long-wavelength phenomena of fluids, that can be expressed as a small gradient expansion of fluid velocities relative to a thermal background. Thus, hydrodynamics is expected to fail for systems which are far-from-equilibrium. The medium produced in pp collisions at LHC and RHIC energies is an example of such a system. However, recent...
Hydrodynamic expansion and jet quenching are responsible for the production of low and high transverse-momentum ($𝑝_𝑇$) particle in heavy-ion collisions, respectively. However, it is still a challenge to simultaneously describe hadron nuclear modification factor $𝑅_{𝐴𝐴}$ and elliptic flow $𝑣_2$, especially in the intermediate $𝑝_𝑇$ region of 2<$𝑝_𝑇$<10 GeV/c. In this talk, we combine...
Recent measurements reveal that J/ѱ yields increase with increasing charged-particle multiplicity in pp and p—Pb collisions at the LHC. Different mechanisms have been proposed to explain this observation. One of them is the influence of multiple parton interactions (MPI) in the initial state of the collision. Measurements of the excited charmonia, as the ѱ(2S) state, state as a function of...
We present the scale dependence of the jet-medium interactions seen in the modification of jet substructure observables in high-energy heavy-ion collisions by systematic studies with JETSCAPE 3, a publicly available software package of a framework for Monte Carlo event generators [1]. In high-energy heavy-ion collisions, jet partons interact with the quark-gluon plasma medium while changing...
The Compressed Baryonic Matter experiment (CBM) at FAIR aims to investigate the high net baryon density and moderate temperature region of the QCD phase diagram, using collisions of heavy ions at center-of-mass energies of a few GeV per nucleon. Anisotropic transverse flow is among the key observables to study the properties of matter created in such collisions. The CBM performance for charged...
ALICE is the experiment at the LHC specifically designed to study the properties of the quark-gluon plasma (QGP), a deconfined state of matter created in ultrarelativistic heavy-ion collisions. In this context, light-flavour particle production measurements play a key role, as they can probe statistical hadronization and partonic collectivity. Recent measurements in small colliding systems (pp...
In heavy-ion collisions, large transverse momentum partons traverse the colored medium and lose energy via induced gluon radiation and elastic scattering, which modify jet structure relative to jets produced in vacuum. The semi-inclusive recoil jet measurement provides precise, data-driven suppression of the large uncorrelated background and uniquely enables the exploration of medium-induced...
Higher-order cumulants of net-proton distributions are sensitive to the details of the phase structure of the QCD phase diagram. Lattice QCD and QCD-based model calculations indicate that the signs of sixth and eighth-order cumulants have different combinations in the hadronic phase, partonic phase, and near the transition temperature.
In this poster, we report the first measurements of...
Investigation of the femtoscopic correlation functions in heavy ion collisions is an important tool to access the space-time structure of the hadron production of the sQGP. The description of the measured correlation functions is often assumed to be Gaussian or exponential, but a detailed analysis reveals that the statistically correct assumption is a generalized Gaussian, the symmetric...
The evolution of leading partons and jets through deconfined QCD matter is a multi-scale phenomenon and remains as one of the challenging problems in heavy-ion physics. To address this, we use the JETSCAPE framework [1] in which the production of the hard parton is factorized from the evolution of the produced QGP. To incorporate various scales involved in the jet-medium interaction during the...
Previous ALICE publications have shown, in pp collisions at the LHC, an increase of the inclusive J/$\psi$ yields as a function of charged-particle multiplicity. Such an increase was found to be stronger than linear, and both J/$\psi$ and multiplicity were measured at midrapidity. The causes for this behavior have been investigated in previous studies with PYTHIA8 and attributed to possible...
Event-by-event pseudorapidity distributions in heavy-ion collisions are sensitive to longitudinal fluctuations. Their shapes can be decomposed using Legendre polynomials, analogous to the Fourier decomposition for anisotropic flow. A longitudinal decomposition for Xe—Xe collisions at $\sqrt{s_{\mathrm{NN}}}=5.44$ TeV and Pb—Pb collisions $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV measured with the...
Anisotropic flow is a key probe of the existence of the quark-gluon plasma. Small collision systems, such as proton-proton (pp) and proton-lead (p--Pb), are usually used to provide the reference data for collisions of heavy nuclei. However, inspection of high-multiplicity p--Pb and pp collisions revealed surprising features, usually attributed to collective effects in heavy-ion...
The precise measurement of the neutral meson production in pp collisions can be used to constrain fragmentation functions and parton density functions needed by pQCD calculations. Additionally, those measurements serve as input for direct photon analyses. Moreover, the dependence of the neutral meson cross section on the event charged-particle multiplicity could give further insight into...
The modification of the substructure of jets due to interactions with a hot QCD medium, the quark-gluon plasma, can be used to study the properties of this medium. Due to the nature of a jet, as a composite object of multiple particles, there are many observables one could construct and study. There is no indication that a single observable will be sufficient to understand the interaction of...
Femtoscopy is a tool that can be used to measure the space-time dimensions of the particle-emitting source created in heavy-ion collisions using two-particle correlations. Additionally to the measurement of the system size, one can extract the average pair-emission asymmetry between two particles with different masses. In this context, the measurement of femtoscopic correlations between...
We postulate that non-perturbative QCD evolution of a single parton in the vacuum will develop the long-range QCD collective effects of a multi-parton system, reminiscent of those observed in high-energy hadronic or nuclear interactions with large final-state particle multiplicity final-state particles [1]. Proton-Proton collisions at the Large Hadron Collider showed surprising signatures of a...
Fluid-dynamical theories are always constructed in terms of an expansion around a given, yet arbitrary, local equilibrium state. This is implemented by the choice of the so-called matching conditions which define the temperature, chemical potential, and velocity of a viscous fluid. Matching conditions are an essential feature of nonequilibrium systems and their consequences to the emergence of...
Heavy-flavor hadrons, containing charm and beauty flavors are believed to be vital probes for the understanding of Quantum Chromodynamics (QCD) in high-energy hadronic collisions: right from the study of production mechanisms in proton-proton ($pp$) collisions to the investigation of Cold Nuclear Matter (CNM) effects in proton-nucleus (p--A) collisions and their suppression in the search of...
State-of-the-art lattice QCD studies of hot and dense strongly interacting matter currently rely on extrapolation from zero or imaginary chemical potentials. The ill-posedness of numerical analytic continuation puts severe limitations on the reliability of such methods. Here we use the more direct sign reweighting method to perform lattice QCD simulation of the QCD chiral transition at finite...
Jets are collimated sprays of hadrons and serve as an experimental tool for studying the dynamics of quarks and gluons. In particular, differential measurements of jet substructure enable a systematic exploration of the parton shower evolution. The SoftDrop grooming technique utilizes the angular ordered Cambridge/Aachen reclustering tree and provides a correspondence between the experimental...
In this talk, I will review the basics of 3+1d quasiparticle anisotropic hydrodynamics (aHydroQP) and highlight some phenomenological comparisons with experimental data at different energies. Then, I will present comparisons of the kaon femtoscopic HBT radii using aHydroQP at 200 GeV where our model shows very good agreement with the experimental data.
Next, I will show predictions of the...
In this poster, measurements of the azimuthal opening angle and transverse momentum correlations between isolated photons and their associated jets, which are sensitive to medium induced parton momentum broadening, are reported for the first time with the high statistics pp and PbPb data recorded in 2017 and 2018. Isolated photon production and their detection techniques will also be summarized.
We explore the transport properties of the QGP matter in the high $\mu_B$ region, where a CEP is incorporated. To this aim we extend the effective dynamical quasi-particle model (DQPM) - constructed for the description of non-perturbative QCD phenomena of the strongly interacting quark-gluon plasma (QGP) - to large baryon chemical potentials, $\mu_B$, including a critical end-point and a 1st...
Collective behaviour of final-state hadrons, and multiparton interactions are studied in high-multiplicity 𝑒𝑝 scattering at a centre-of-mass energy 𝑠√=318 GeV with the ZEUS detector at HERA. Two- and four-particle azimuthal correlations, as well as multiplicity, transverse momentum, and pseudorapidity distributions for charged-particle multiplicities 𝑁ch≥20 are measured. The dependence of...
The very forward energy in hadron-hadron collisions contains information about the fragmentation of the projectile and the target, providing direct insights into the initial stages of high-energy hadronic collisions. By constraining the very forward energy, one can control the event activity in the collision. Results on very forward energy, measured by the ALICE zero degree calorimeters...
The transverse region of di-hadron correlations is known to be
very sensitive to the underlying event (UE), and initial- and
final-state radiation (ISR and FSR). In pp collisions, particle
production in the transverse azimuthal region, with respect to
the leading particle, reaches a plateau for $p^{leading}_{T}>$ 5
GeV/c. In this contribution, a study of the multiplicity...
Transport properties of the matter created in heavy-ion collisions, the quark-gluon plasma (QGP), contain essential information about quantum chromodynamics (QCD). To deepen our understanding of QCD, it is crucial to estimate these transport properties (for instance, specific shear and bulk viscosity) in the light of experimental data as accurately as possible. In this talk, we present our...
There is strong evidence for the formation of small droplets of quark-gluon plasma in $p/d/^{3}$He+Au collisions at the Relativistic Heavy Ion Collider (RHIC) and in $p$+$p$/Pb collisions at the Large Hadron Collider. In particular, the analysis of data at RHIC for different geometries obtained by varying the projectile size and shape has proven insightful. In this talk, we present a new...
We discuss the quantum fluctuations of energy in subsystems of hot relativistic gas for both scalar and spin half particles. For small subsystem sizes, we find a substantial increase of fluctuations compared to those known from standard thermodynamic considerations. However, if the size of the subsystem is sufficiently large, we reproduce the result for energy fluctuations in the canonical...
We study the thermalization of highly energetic partons in a high-temperature QCD plasma. We investigate the non-equilibrium dynamics using an effective kinetic description of QCD, following the evolution of a highly energetic parton from the hard momentum scales all the way to the medium scales, while keeping track of the recoil onto the medium [1-2]. We find that successive radiative...
The Compressed Baryonic Matter experiment (CBM) aims to study the area of the
QCD phase diagram at high net baryon densities and moderate temperatures. It is predicted by Three-fluid Hydrodynamics-based Event Simulator (THESEUS) that one of the signatures of phase transition is a change in shape of the mid-rapidity curvature and yield.
In this contribution we will present CBM performance for...
Properties of dijets may provide sensitive probes of jet quenching in Quark-Gluon Plasma. Dijet invariant mass measurements in small systems provide an essential baseline for such studies in Pb-Pb collisions. In this poster, we present the first measurements of dijet invariant mass in minimum bias pp and p-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV by ALICE. Jets are clustered using the...
High statistics data sets from experiments at RHIC and the LHC with small and large collision species have enabled a wealth of new flow measurements, including the event-by-event correlation between observables. One exciting such observable $\rho$($v^2_n$,[$p_T$]) gauges the correlation between the mean transverse momentum ($p_T$) of particles in an event and the various flow coefficients...
Femtoscopic correlations are measured over a broad multiplicity range using data from the LHC Run II collected by the CMS experiment for small colliding systems. Studies are performed for correlations of charged hadrons produced in proton-proton (pp) collisions at $\sqrt{s} = $ 13 TeV and for correlations with all pair combinations of $\text{K}^{0}_{\text{S}}$, $\Lambda$ and...
NA61/SHINE conducts the search for a hypothesized critical point of strongly interacting matter by scanning in collision energy and mass of colliding nuclei. In this field, one of the key methods is to search for the intermittency signal that, if observed, can be related to the effect of the system self-similarity in the vicinity of a possible critical point. This would lead to the power-law...
The magnetic fields generated in non-central heavy-ion collisions are among the strongest fields produced in the Universe, reaching magnitudes comparable to the scale of the strong interactions. Backed by model simulations, the resulting field is expected to be spatially modulated, deviating significantly from the commonly considered uniform profile. In this work, we present the next step to...
Hard partonic scatterings serve as an important probe of quark-gluon-plasma (QGP) properties. The properties of jets and their constituents can provide a tool for understanding the partonic energy loss mechanisms. Low momentum jets offer a unique window into partonic energy loss because they reconstruct the partons which have lost a significant amount of energy to the QGP medium. The main...
Realistic modeling of nucleus-nucleus collisions at finite baryon chemical potential is necessary to extract the location of the critical point on the QCD phase diagram and to understand the findings of the recently concluded Beam Energy Scan (BES) program at RHIC and the future planned experiments at FAIR and NICA. We propose a hydrodynamic model with three new elements. Firstly, we present a...
Quantum chromodynamics (QCD), the fundamental theory of strong interactions, allows the existence of exotic hadrons other than mesons and baryons. An exotic hadron consisting of six quarks is called a dibaryon, and a dibaryon containing strange quarks (multi-strangedibaryon) has not yet been discovered. An exotic hadron consisting of four quarks and an antiquark is called a pentaquark, and the...
The thermodynamical properties of the high-temperature and high-density system produced in relativistic heavy-ion collisions can be understood with a systematic study of the produced hadrons' transverse momentum ($p_{\rm T}$ ) spectra. The $p_{\rm T}$ spectra of these hadrons can be described well by a distribution using the Tsallis statistics. The Tsallis parameters $q$ and $T$ measure the...
The PHENIX experiment measured two-particle Bose- Einstein quantum-statistical correlations of charged kaons in Au+Au collisions $\sqrt{s_{NN}}=200$ GeV collision. The correlation functions are parametrized assuming that the source emitting the particles has a Lévy-shaped characterized by the $\alpha$ Lévy exponent and the $R$ Lévy scale. By introducing the $\lambda$ intercept parameter we...
Recently the PHENIX Collaboration has made available two-particle correlation Fourier coefficients for multiple detector combinations in minimum bias p+p and 0-5% central $p$+Au, $d$+Au, $^3$He+Au collisions at 200 GeV (arXiv:2107.06634). Using these coefficients for three sets of two-particle correlations, azimuthal anisotropy coefficients $v_2$ and $v_3$ are extracted for midrapidity charged...
The different modification of quark- and gluon-initiated jets in the quark-gluon plasma produced in heavy-ion collisions is a long-standing question that has not yet received a definitive answer from experiments. In particular, the relative sizes of the modification of quark and gluon jets differ between theoretical models. Therefore a fully data-driven technique is crucial for an unbiased...
The study of correlation and fluctuation of event-by-event mean transverse momentum ($p_\mathrm{T}$) is a useful tool to understand the dynamics of the system produced in ultrarelativistic heavy-ion collisions. The measurement of higher-order fluctuations of mean-$p_\mathrm{T}$ can help in probing the hydrodynamic behavior of the system and is considered to be a direct way of observing...
One of the main goals of RHIC beam energy scan (BES) program is to search for the signatures of the QCD critical point in heavy-ion collisions. Local density fluctuations near the QCD critical point exhibit strong intermittency which is revealed as the scale (power-law) dependence of scaled factorial moments on phase-space resolution. The scaling exponent is related to the critical component...
Jet fragmentation can be studied using the transverse momentum ($j_T$) and longitudinal momentum fraction ($z$) of constituent particles. The $j_T$ distributions of jet fragments have been measured in pp and p—Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV with ALICE, and various parton-shower models reasonably describe the pp results. In this analysis we carry out more detailed measurements of...
Two-particle charge-dependent correlations (balance functions) are sensitive to the production and transport of conserved quantum numbers in the medium created in hadronic collisions. In this con- tribution, recent ALICE measurements of the balance functions of charge, strangeness, and baryon numbers are presented. Balance functions for all combinations of identified charged-hadron ($\pi$, K,...
In non-central heavy-ion collisions, a large orbital angular momentum is created along the direction opposite to the reaction plane, which will be transferred to the spin of quarks through the spin-orbit coupling in parton scatterings. In our recent work, we formulate an improved coalescence model through spin density matrix with phase space dependence, which provides a uniform way to compute...
The measurement of jet deflection in heavy-ion collisions promises to provide unique and incisive insight into the physics of jet quenching and the quasi-particle nature of the QGP. However, observation of large-angle jet deflection favors using low transverse momenta ($p_{\rm T}$) jets, which is challenging in the high-background environment of heavy-ion collisions. The semi-inclusive...
A system of gluon fields generated at the earliest phase of relativistic heavy-ion
collisions can be described in terms of classical fields. Numerical simulations show that the system is unstable but a character of the instability is not well understood. With the intention to systematically study the problem, we analyze a stability of classical chromomagnetic and chromoelectric fields which...
We study the thermodynamic properties, such as the pressure and the entropy density, of a gas of glueballs by considering the contribution of the tower of various glueball states obtained by using recent lattice calculations as well as other model results. We also include, to our knowledge for the first time, the effect of glueball-glueball interaction on thermodynamic properties. The results...
Different than for inclusive jets, leading jet cross sections constitute normalized probability distributions for the leading jet to carry a longitudinal momentum fraction relative to the initial fragmenting parton. The formation and evolution of leading jets can be described by jet functions that satisfy non-linear DGLAP-type evolution equations. We present a parton shower algorithm that...
We employ an effective kinetic theory of Quantum Chromo Dynamics (QCD) to study the pre-equilibrium dynamics of the Quark-Gluon Plasma (QGP) at zero and finite net-baryon density. By investigating the dynamics of the energy-momentum tensor and the conserved charges, we determine the relevant time and temperature scales for the onset of viscous hydrodynamics, and quantify the evolution of the...
Relativistic heavy-ion collisions can study properties of nuclear matter in high-energy experiments like the STAR experiment. Femtoscopy, which relies on information carried by the particles produced in the collisions, is one of methods to learn about the bulk matter. By studying the quantum statistical effects and final state interactions between two particles, one can study spatial and...
Proton-ion collisions at the LHC and RHIC have yielded unexpected trends, notably in measurements of jet nuclear modification factors at different collision centralities. Recent preliminary measurements from STAR in p+Au collisions at $\sqrt{s_{{\rm NN}}}=200$ GeV demonstrate inherent correlations between high-$Q^{2}$ parton scatterings and event activity (EA), measured using either detectors...
In 2018, STAR installed the Event Plane Detector (EPD) with a pseudorapidity coverage of $2.15<|\eta|<5.09$. The EPD has enhanced STAR's capabilities in triggering, centrality measurement and event plane determination. Due to its fine radial granularity, it can also be utilized to measure pseudorapidity distributions of charged particles. In order to make such a measurement, the response of...
Hadronic resonances are interesting probes of the hot and dense matter created in the heavy-ion collision. Due to their short lifetimes, resonances are useful tools to understand the mechanism of particle production and properties of the hadronic phase created after the collision. The yield of resonances might be modified with respect to expectations due to effects such as rescattering and...
The quark model has proven successful in describing the basic building blocks of strongly interacting particles in the Standard Model, where hadronic states consist of quarks and gluons. At the same time, Lattice QCD predicts the possibility of glueball candidates in the mass range 1550-1750 MeV/$c^{2}$, which have never been observed.
The experimental search for the existence of mesons...
We derive Boltzmann equations for massive spin-1/2 fermions with local and nonlocal collision terms from the Kadanoff--Baym equation in the Schwinger--Keldysh formalism, properly accounting for the spin degrees of freedom. The Boltzmann equations are expressed in terms of matrix-valued spin distribution functions, which are the building blocks for the quasi-classical parts of the Wigner...
The main goal of the ALICE experiment is to study the physics of strongly interacting matter, including the properties of the Quark-Gluon Plasma (QGP). The relative production of strange hadrons with respect to non-strange hadrons in heavy-ion collisions was historically considered one of the signatures of QGP formation. However, recent measurements in proton-proton (pp) and proton-lead (p-Pb)...
We study the thermal properties of scalar quantum field theories (QFTs) involving 3-leg and 4-leg interaction terms, with special attention on the role of bound states and resonances. Within a suitable unitarization scheme, for which the employed QFT is unitary, finite, and well defined for each value of the coupling constant, we calculate the scattering phase shifts, whose derivatives are...
Jets are collimated sprays of particles produced from the fragmentation and hadronization of hard-scattered partons in high energy hadronic and nuclear collisions. Jet properties are sensitive to details of parton showering processes and expected to get modified in the presence of a dense partonic medium. Recently features similar to those in heavy-ion collisions have been observed in high...
In ultra-central heavy-ion collisions, the effects of event-by-event fluctuations on anisotropic flow are relatively more pronounced due to less geometrical anisotropy of initial transverse profiles. The magnitudes of elliptic flow $v_2$ and triangular flow $v_3$ were reported to be almost the same value in ultra-central collisions [1]. Dynamical models based on relativistic viscous...
Jets are excellent probes for the study of the deconfined matter formed in heavy ion collisions. In particular, jet substructure measurements can help us understand the interaction dynamics of high-energy partons with the quark-gluon plasma. We introduce a new infrared and collinear safe observable: jet energy flow measurements using jets reconstructed with different resolution parameters $R$....
The strongly intensive quantity $\Sigma$ is a new observable, introduced recently to the domain of heavy-ion physics. In superposition models which assume independent particle production from statistically identical sources, $\Sigma$ is insensitive to the number of sources and its fluctuations, contrary to the standard forward-backward correlation coefficient ($b_{\rm corr}$). Therefore, it...
In relativistic heavy ion collisions, the event-by-event mean transverse momentum ($\langle{p_{T}}\rangle$) fluctuations are sensitive to fluctuations in overlap area and reflect the nature of initial-state fluctuations in energy density. We present a cumulant framework to measure the event-by-event $\langle{p_{T}}\rangle$ fluctuations up-to $4^{\mathrm{th}}$ order which is then validated...
Short-lived hadronic resonances are very useful to probe the late-stage evolution of ultra-relativistic heavy-ion collisions. Since their lifetimes are comparable to the hadronic phase timespan, their measured yields are modified via rescattering and regeneration processes. The suppression of the K$^{*0}$/K ratio in central Pb--Pb collisions compared to pp interactions already hints at the...
Heavy-flavour (charm and beauty) jets are excellent probes to study Quantum Chromodynamics (QCD). Their precise measurements in proton-proton collisions are used to verify perturbative QCD calculations and improve our modelling capabilities by constraining Monte Carlo generators. They also serve as the reference measurements for more complex systems such as Pb–Pb collisions, helping to...
Hydrokinetic formalism is a deterministic set of relaxation type equations that tracks the evolution of n-point correlation functions of stochastic hydrodynamic quantities. Hydrokinetic formalism is a complementary approach to solving the Stochastic Differential Equations (SDE) for fluctuating hydrodynamics. Hydrokinetics is comparatively easier to solve than the SDEs, which need to deal with...
Relativistic hydrodynamics has been successful in describing the evolution of Quark-Gluon Plasma, as well as understanding and predicting experimental measurements highlighting the collective behavior of the observed hadrons created in relativistic heavy-ion collisions. In parallel with the remarkable progress made in numerical fluid dynamics, the study of analytical solutions remains helpful...
Recent results in high-multiplicity pp collisions show interesting features similar to those that are associated to the formation of a quark-gluon plasma in heavy-ion collisions [1]. Investigating the modification of the intra jet properties as a function of event multiplicity in pp collisions can provide deeper insight into the nature of these effects.
We will present the latest...
Very recently, a non-equilibrium effective field theory framework has been formulated for fluctuating hydrodynamics [1]. In this talk, we present examples of applying this novel formalism to study the properties of QCD-like systems. In the first example, we study the dependence of the conductivity/resistivity on the external magnetic field in a chiral medium (the constituent of which includes...
The ratio of strange to non-strange hadron yields increases from low- multiplicity to high-multiplicity hadronic interactions, reaching values observed in heavy-ion collisions. The ALICE experiment investigates the microscopic origin of this striking phenomenon by performing dedicated multi-differential analyses in pp collisions at $\sqrt{s}$ = 13 TeV.
To separate strange hadrons...
The measurement of azimuthal correlations between two particles is a powerful tool to investigate the properties of strongly-interacting nuclear matter created in ultra-relativistic heavy-ion collisions. In particular, studying the near-and away-side hadron yields associated with trigger particles can provide important information to understand both the jet-medium interaction and hadron...
The study of collective phenomena in ultrarelativistic heavy-ion collisions is nowadays to a great extent built on the so-called flow amplitudes $v_n$ and symmetry planes $\Psi_n$. Both appear as two distinct degrees of freedom in the parametrization of the azimuthal distribution of the produced particles, which is used in the study of the quark-gluon plasma (QGP). Investigating the complex...
In this talk I review recent progress in resummed perturbative calculations of the equation of state of QCD and N=4 supersymmetric Yang-Mills (SUSY) theory. In the case of QCD, I will review progress that has been made using hard-thermal-loop perturbation theory (HTLpt) at finite temperature and quark chemical potential(s), focussing on recent NNLO HTLpt predictions for the quadratic and...
The interplay of the chiral anomaly and the strong magnetic field (~10$^{15}$ T) created in the off-central heavy-ion collisions could give rise to a collective excitation in the quark-gluon plasma called the Chiral Magnetic Wave (CMW), which can be experimentally sought by the charge asymmetry ($A_{\rm ch}$) dependence of elliptic flow $v_2$ of positively and negatively charged hadrons....
The phase transition from hadronic matter to quark-gluon plasma (QGP) is a phenomenon that occurs under extreme conditions of high temperature and high density, as achieved at the relativistic heavy ion collider (RHIC). The QGP causes energy loss of high momentum particles which is observed as suppression of high momentum hadron production in A+A collisions relative to p+p collisions. The...
This talk presents a novel instability in the Chern-Simons (or axionic) magnetohydrodynamics (MHD), arising from the spatial inhomogeneity of the axion-like field. In particular, this instability amplifies the Alfven waves in certain regions of spacetime in a way that is clearly parity-violating. The Aflven velocity reaches the speed of light in such regions, but it never exceeds it.
Internal properties of jets and their production in small collision systems (pp and p--Pb) are tightly connected to perturbative and non-perturbative aspects of quantum chromodynamics (QCD), such as cold nuclear matter effects. Recent studies of high-multiplicity final states of small collision systems also exhibit signatures of collective effects that are thought to be associated with hot and...
First six cumulants of proton number are calculated in the statistical resonance gas model with chemical potentials for every stable identified hadron species. The chemical potentials are chosen in such a way that the average particle numbers after decay of resonances are kept constant independently of temperature and equal to the values given at the chemical freeze-out. This corresponds to a...
In this contribution, we present a first factorial moment analysis performed on the multiplicity distributions of charged particles produced in the Pb$-$Pb collisions at $\sqrt{s_{\rm{NN}}}$=2.76 TeV, recorded with the ALICE detector at the LHC. The normalized factorial moments (NFM) of spatial configurations of charged particles in two-dimensional angular ($\eta,\varphi$) phase space,...
Direct photons are widely used probe to study the properties and evolution of the hot and dense medium (e.g. QGP) produced in high energy heavy-ion collisions. Being color neutral, they do not interact strongly with the medium and are produced at all stages of the collision.
A universal scaling of the direct photon yield with charged particle multiplicity has been observed for a wide range...
Recent measurements in high multiplicity proton-proton collisions have shown the emergence of several features that are reminiscent of QGP phenomenology, one of which is the enhanced production of strange and multi-strange hadrons. Strange hadron production represents a key probe to study QGP formation in hadronic collisions as well as to understand the mechanisms behind hadronisation.
In...
Non-equilibrium Green’s functions provide an efficient way to describe the pre-equilibrium evolution of macroscopic quantities in early stages of heavy-ion collisions.
Within the kinetic theory framework we use moments of the distribution functions to calculate time dependent non-equilibrium Green’s functions describing the evolution of initial energy/momentum/charge perturbations [1]. Using...
With the tremendous accomplishments of RHIC and the LHC experiments and the advent of the future Electron-Ion Collider on the horizon, the quest for compelling evidence of the color glass condensate (CGC) has become one of the most aspiring goals in the high energy quantum chromodynamics research. Pursuing this question requires developing the precision test of the CGC formalism. By...
We develop a general decomposition of an ensemble of initial density profiles in terms of an average state and an orthonormal basis of modes that represent the event-by-event fluctuations of the initial state. The basis is determined such that the probability distributions of the amplitudes of different modes are uncorrelated. Based on this decomposition, we quantify the different types and...
Measurements of strange hadron production in pp and p-Pb collisions had been used as a reference for the study of the so-called strangeness enhancement effect, occurring in heavy ion collisions where QGP formation is observed.
Recently, the ALICE Collaboration studied strangeness production in pp interactions, unveiling unexpected features in the strange hadron to pion yield ratios. These...
The jet transverse momentum diffusion coefficient $\hat{q}$ is an important transport coefficient governing the radiative energy loss of a parton propagating the Quark-Gluon Plasma (QGP) created in Heavy-Ion Collisions. Based on perturbative arguments [1], which were recently extended to next-to-leading order [2], the dimensionless ratio $\hat{q}/T^3$ was shown to be connected with the...
Multiplicity distributions in e+e- and pp collisions analysed via combinants exhibit oscillatory behavior of the modified combinants. The possible sources of these oscillations and their impact on our understanding of the multiparticle production mechanism were discussed [1-3]. The set of combinants, Cj provides a similar measure of fluctuations as the set of cumulant factorial moments, Kq,...
Exploring the shape of the pair-source function for particles such as pions or kaons has been an important goal of heavy-ion physics, and substantial effort has been made in order to understand the underlying physics behind the experimental observations of non-Gaussian behavior. In experiments, since no direct measurement is possible, femtoscopic (momentum) correlations are utilized to gain...
Previous ALICE results indicate a stronger than linear increase of the inclusive normalized J/$\psi$ yield with charged-particle multiplicity, both measured at mid-rapidity, in proton-lead collisions at $\sqrt{s_{NN}}=5.02$ TeV. The corresponding ALICE results on proton-proton collisions at$\sqrt{s}=13$ TeV provide a clearer picture of a stronger than linear increase.
In PYTHIA8, this...
Two-particle differential correlators of particle numbers ($R_2$) and particle transverse momenta ($P_2$ and $G_2$), recently measured in Pb-Pb collisions, emerged as powerful tools to gain insights into particle production mechanisms and infer transport properties such as the ratio of shear viscosity to entropy density of the medium created in Pb-Pb collisions. In this talk, recent ALICE...
Since the first positive measurement of the Λ-hyperon global spin polarization in heavy-ion collisions by STAR collaboration in 2017, the understanding of the nature of this phenomenon is one of the most intriguing challenges for the heavy-ion physics community. As relativistic fluid dynamics celebrates multiple successes in describing collective dynamics of the QCD matter in such reactions,...
The pre-hydrodynamic evolution of a heavy-ion collision can have a considerable effect on final state observables, notably those related to the transverse momentum spectra of final particles [1]. In this work, we study two different collision systems, namely Pb-Pb and p-Pb, utilising a state-of-the-art hybrid model. We extend our previous results [1] on the effects of pre-hydrodynamical models...
The ALICE Collaboration presents results of a search for jet quenching effects in high multiplicity pp collisions at $\sqrt{s} = 13~\rm{TeV}$ by measuring the semi-inclusive acoplanarity distribution of charged-particle jets that recoil from a high transverse momentum trigger-track. The search for jet quenching is performed by comparing the acoplanarity distributions measured in high...
The McLerran-Venugopalan Model (MV) of Color Glass Condensate for two colliding nuclei has been solved in the past using numerical methods and recursive analytic solution. On the other hand, in the weak field limit explicit analytic solutions in transverse momentum space have, in principle, been known for quite some time. Based on the latter we derive analytic expressions for gluon 2-point...
We explore the thermalization of energetic partons in quark-gluon plasma medium by analyzing the medium response effect on jet substructure observables. In high-energy heavy-ion collisions, jets become more populated by soft partons through the induced radiation and scatterings in the medium. Consequently, the energies of some soft jet partons reach the typical energy of the medium...
Measurements of neutral mesons in small collision systems can serve as a baseline to understand modifications in heavy-ion collisions, where a QGP is formed.
These measurements can also be used to test pQCD predictions and to constrain fragmentation functions as well as parton distribution functions.
Furthermore, a good understanding of particle production enables the measurement of direct...
Measurements of long-range correlations are one of the important tools for evaluation of the interplay between the initial- and final-state effects. Recently, non-vanishing second Fourier harmonic $\it{v}_{2}$ has been observed in small collision systems such as pp and p--Pb collisions. In this contribution, we present measurements of $\it{v}_{2}$ extracted from long-range two-particle...
We study theoretical uncertainties in the hydrodynamic description of relativistic heavy-ion collisions by examining the full nonlinear causality conditions [1] and quantifying their effects on flow observables [2]. The causality conditions impose physical constraints on the maximum allowed values of inverse Reynolds numbers during the hydrodynamic evolution. We develop a new numerical scheme...
The determination of the hot QCD pressure has a long history, and has --
due to its phenomenological relevance in cosmology, astrophysics and heavy-ion collisions — spawned a number of important theoretical advances in perturbative thermal field theory applicable to equilibrium thermodynamics.
In particular, the long-standing infrared problem that obstructs the perturbative series has been...
The electromagnetic fields produced by non-central heavy ion collisions are extremely powerful and give rise to a plethora of fascinating subjects in strongly interacting matter. Their evolution is a significant and unresolved issues. Because the relaxation time of the hot QCD matter to the electromagnetic fields is comparable with the lifetime of external electromagnetic field, we question,...
We argue that a detailed analysis of the spin aligement of vector mesons can serve as a probe of some aspects of spin dynamics in the vortical fluid for which there have been quite a few theoretical developments but relatively little phenomenology:
The degree of relaxation between vorticity and parton spin polarization, and the degree of coherence of the hadron wavefunction at...
Quarks and gluons traversing a QCD medium may lose energy through a variety of processes, including medium-induced radiation sensitive to their QCD color factor.
The color-charge dependence of the parton-medium interaction is a critical component in all jet energy loss models and generally in heavy-ion physics phenomenology. In this talk, the color charge dependence of jet-medium...
We study fluctuations of particle number in the presence of critical point by utilizing molecular dynamics simulations of a classical Lennard-Jones fluid in a periodic box. The numerical solution of the $N$-body problem naturally incorporates all the relevant effects like physics of the correlation length, exact conservation laws, and finite size effects, allowing us to study the luctuation...
NA61/SHINE is a fixed-target experiment at the CERN SPS. Its spectrometer has unique properties including large particle acceptance and precise momentum measurement. These properties together with high statistics of collected proton-proton collisions at beam momentum 158 GeV/c allow analyzing the transverse polarization of $\Lambda$ hyperons produced in the primary vertex.
The opportunities...
The theory of jet quenching has been steadily evolving in order to incorporate the effects of having a longitudinally evolving plasma. On the other hand, the transverse dynamics of the medium evolution has been largely ignored due to the fact that its effects are suppressed by powers of the energy of the probe. Recently, a calculation of the effects of medium motion on transverse momentum...
In this talk, we present a study of direct photons in relativistic nuclear collisions, along with the production of hadrons, from RHIC Beam Energy Scan (BES) to LHC energies. Thermal photons are soft and penetrating probes of the strongly-coupled nuclear matter created in relativistic heavy-ion collisions. Their spectrum and momentum anisotropies remember the QGP’s chemistry evolution and its...
Two-component hydrodynamic model with jets, HYDJET++, is employed to analyse the data on elliptic flow correlations at low (pT < 1.25 GeV/c) and high (pT > 14 GeV/c) transverse momenta in Pb+Pb collisions at \sqrt{sNN} = 5.02 TeV. Because of these two mechanisms, describing soft and hard processes, the model calculations restored by the four-cumulant method reproduce the centrality dependence...
We develop a new parametric 3-dimensional initial condition for low-energy heavy-ion collisions based on collision geometry for a multistage hybrid framework. The longitudinal structure of the collision profile is constrained by rapidity-dependent experimental measurements, especially the directed flow of pions and protons (i.e., $v_1(y)$). We introduce a baryon stopping parameter which...
Nuclear deformation is an ubiqutous phenomenon for most atomic nuclei, reflecting collective motion induced by interaction between valance nucleons and shell structure. In most cases, the deformation has a quadrupole shape that is charactorized by overall strength $\beta_2$ and triaxiality $\gamma$ (prolate $\gamma=0$, obolate $\gamma=\pi/3$ and triaxial otherwise). Collisions of deformed...
Increasingly many studies have involved the use of Bayesian statistics in estimating the transport properties of quark-gluon plasma through hydrodynamic calculations. So far, most of these studies have obtained their estimates in Pb-Pb collision systems at varying center-of -mass energies. It has been since learned that the inclusion of multiple collision configurations and high harmonic...
Two-particle correlations are a widely used tool for studying relativistic nuclear collisions. Multiplicity fluctuations have been studied as a possible signal for QGP and the QCD critical point. Momentum correlations and covariances of momentum fluctuations, which arise from the same correlation function, have also been used to extract properties of the nuclear collision medium such as the...
Building upon Ref. [1], we present an improved three-dimensional dynamical initialization model for heavy-ion collisions, implementing local energy-momentum conservation and baryon charge fluctuations at string junctions [2]. These improvements lead to an excellent description of the charged hadron and net proton rapidity distributions in Au+Au collisions from 7.7 to 200 GeV [3]. Based on...
The quark-gluon plasma formed in heavy-ion collisions has a large momentum anisotropy, especially during early stages of collisions. For jet partons this leads to momentum broadening which is not isotropic in the parton's transverse plane. In this talk we discuss such anisotropic momentum broadening of jets in detail and evaluate how it changes the radiation of hard gluons, and gives rise to a...
Measuring the jet substructure in heavy-ion collisions provides exciting new opportunities to study detailed aspects of the dynamics of jet quenching in the hot and dense QCD medium created
in these collisions. In this talk, we present new ATLAS measurements of jet substructure performed using various jet (de)clustering and grooming techniques. Measurements of inclusive jet suppression...
Despite almost a decade of work, the absence of jet-modification in small systems is yet to be satisfactorily explained. Although JEWEL (Jet Evolution With Energy Loss) is a Monte Carlo (MC) generator designed to study the evolution of jets with a variety of background media, the publicly available versions are not able to simulate small systems. We present the first results using an...
The ALICE experiment has significantly upgraded its detectors. It will make possible to perform new measurements in the Ultra Peripheral Collisions (UPCs) of lead nuclei for the integrated luminosity of $\mathcal{L}^{\rm Pb-Pb}=13$/nb during Run 3 and Run 4. For Run 5 and beyond, a completely new next-generation heavy-ion experiment ALICE 3 is proposed. The new detector system will cover
much...
The Compressed Baryonic Matter (CBM), currently under construction at the Facility for Anti-proton and Ion Research (FAIR) accelerator complex in Darmstadt, Germany aims to explore the QCD phase diagram at high baryon densities. Till date, no dilepton data have been collected in heavy-ion collisions at beam energies between 2A and 40A GeV. CBM aims to perform pioneering measurements of lepton...
We discuss mean field theory of Quarkyonic matter at zero temperature. this field theoretical description of quarkyonic matter consisting of quark, nucleon and ghost fields. The ghosts are present to cancel over-counting of nucleon states that are Pauli blocked by the quark Fermi sea. We treat the nucleons with contact interactions in mean field approximation and the quarks without mean field...
Measurements of two-particle correlations in $pp$ collisions show the presence of long-range correlations along $\Delta\eta$ that are strikingly similar to those seen in heavy-ion collisions.
In larger systems, the long-range correlations are known to arise from the collective dynamics of the produced quark-gluon plasma (QGP). The similarity between the $pp$ and heavy-ion measurements raises...
Recently, the so-called relative transverse activity classifier, $R_T$, has been proposed as a tool to disentangle the particle production originated from the soft and hard QCD processes in proton-proton (pp) collisions. $R_T$ is a useful quantity to study particle production in events with exceptionally large or small activity in the transverse region with respect to the event-averaged...
High-pt theory and data are traditionally used to explore high-pt parton interactions with QGP, while bulk QGP properties are commonly explored through low-pt data. However, rare high-pt light and heavy flavor can also be a powerful tool for inferring bulk QGP properties, as they are sensitive to global QGP parameters. A prerequisite for such QGP tomography is a proper description of high-pt...
The photon-photon interaction in ultra-relativistic heavy-ion collision is a source of the $(e^+,e^-)$ pairs. The photon-photon fusion leads to the lepton creation in the broad configuration space around ''collision'' point. Those created close to heavy nuclei may undergo strong interaction with them.
The impact parameter space distributions of electrons and positrons are calculated within...
The influence of initial state fluctuations on elliptic e2 and triangular e3 eccentricities and on elliptic v2 and triangular v3 flows in relativistic heavy ion collisions is studied within three Monte Carlo models. The models are based on (i) number of participant nucleons, (ii) number of binary collisions, and (iii) partonic energy density in color glass condensate (CGC) phase,...
The Quark-Gluon Plasma, a state of matter characterized by its extreme energy density and temperature generated in heavy-ion collision experiments, is expected to modify hard-scattered partons traveling through it and, consequently, the jets they produce. Analyses regarding jets may recover information about the medium and its partonic energy-loss mechanism. This work applies the Monte Carlo...
We present a comparison of observables related to photon-triggered jets for different collision energy systems, at LHC and RHIC energies, with the latest update of the JETSCAPE framework [1,2]. In heavy-ion collisions, multiple probes are used to study the properties of the Quark-Gluon Plasma (QGP). Photons can be produced at any stage of the heavy-ion collision. Since photons do not interact...
We demonstrate that hard dijet production via inelastic diffraction is a promising channel for probing gluon saturation at the Electron-Ion Collider. Diffraction refers to a process in which there is a large rapidity gap between the produced jets and the nuclear target, while inelastic means that the two hard jets - a quark-antiquark pair generated by the decay of the virtual photon - are...
The measurement of hadronic resonance production in heavy-ion collisions at the LHC has led to the observation of a prolonged hadronic phase after hadronisation. Due to their short lifetime, resonances experience the competing effects of regeneration and rescattering of the decay products in the hadronic medium. Studying how the experimentally measured yields are affected by these effects can...
Hard probes, due to their large momenta (or masses), are produced only through hard interactions with large momentum transfer at the earliest phase of a heavy-ion collision. They then propagate through the evolving medium probing QCD matter at different energy scales and different phases of the fireball evolution. During this propagation heavy quarks and high-$p_T$ partons lose a substantial...
The production of (anti)deuterons in relativistic heavy-ion collisions is currently well described by two models that point to different mechanisms of particle creation. The first of the two, the coalescence model, describes the (anti)deuteron’s creation as a result of final-state interactions among (possibly off-shell) nucleons after the chemical freeze-out. The second, the thermal model...
“Hybrid Hadronization” is a Monte Carlo package that hadronizes systems of partons. It smoothly combines quark recombination, applicable when distances between partons in phase space are small, and string fragmentation appropriate for dilute parton systems, following the picture outlined by Han et al. [PRC 93, 045207 (2016)]. Hybrid Hadronization can be applied to a variety of systems from...
Jet substructure applied to a heavy-ion environment can provide valuable information about jet-medium interaction. This class of observables, mostly inherited from proton-proton collisions, is still far from being fully exploited as a tool for QGP tomography. So far, measurements are restricted to quantities that provide an average quantification of the medium parameters, missing the critical...
Because photons and dileptons are unlikely to interact after production within a quark-gluon plasma (QGP), they can probe the inner dynamics of this strongly interacting system. To leading order in the electromagnetic coupling and all orders in the strong coupling, the observable emission rates can be determined from the QCD vector channel spectral function. The resummed next-to-leading order...
Recently the splitting of elliptic flow $v_2$ at finite rapidities has
been proposed to be the result of global vorticity in non-central
relativistic heavy ion collisions [1]. Here we confirm the existence
of the $v_2$ splitting. However, we show that this left-right $v_2$
splitting (on opposite sides of the impact parameter axis) is mostly
due to the non-zero directed flow $v_1$ at...
We present a study of photon-photon scattering in the mass range $W_{\gamma \gamma}<5$ GeV. We extend earlier calculations of this cross section for $W_{\gamma \gamma}>5$~GeV into the low mass range where photoproduction of the pseudoscalar resonances $\eta$, $\eta'(958)$ contributes to two-photon final states. We present the elementary photon-photon cross section as a function of diphoton...
Because of the increasing gluon density towards small-$x$, a regime where these densities reach a saturation ($Q_{\rm sat}$) is expected. The observation of this gluon saturated matter has several consequences to particle production and is a matter of an entire effective field theory, the Color Glass Condensate. The Large Hadron Collider beauty (LHCb) experiment has a privileged geometry for...
Jets produced in heavy-ion collisions provide important information about the medium that they traverse. Their seeds, highly energetic partons that are created via hard scatterings during the collision, are affected by all different stages of the medium, including the pre-equilibrium precursor state of the quark-gluon plasma, which is known as the glasma. We will report on our numerical...
We revisit the picture of jets propagating in the quark-gluon plasma. In addition to vacuum radiation, related to the high initial virtuality of a jet, jet particles scatter on the medium constituents resulting in induced emissions. Analytical approaches to resumming these interactions have traditionally dealt separately with multiple, soft [1,2], or rare, hard scatterings [3,4]. A full...
The BEST collaboration’s equation of state (EoS) maps a 3D Ising model onto the lattice QCD EoS but contains 4 free parameters related to the size, location, and spread of the critical region across the QCD phase diagram. However, certain combinations of those 4 free parameters lead to acausal ($c_s^2>1$) or unstable ($\chi_2^B<0$) realizations of the EoS that should not be considered. Here,...
The aim of this work was to investigate the properties of a new, simple model of the nucleus+nucleus collisions at high energy, and its applicability to the CERN SPS energy regime. The model was uniquely based on the system's geometry and local energy and momentum conservation in the quark gluon plasma produced in the reaction.
We studied Pb+Pb collisions at $\sqrt{s_{NN}}$ = 17.3 GeV and...
The study of femtoscopic correlations of photon pairs, emitted from heavy-ion collisions, can serve as an unique probe of the evolution of the source in space and time. Unlike commonly used charged particles photons are not subject to strong, nor electromagnetic interactions. These properties imply no distortion of the information carried by $γ$ from the point of their creation up to the...
Recently, we developed a framework to evaluate the single-inclusive gluon emission spectrum without further assumptions, including full resummation of multiple scatterings. In this talk, we compare this formalism with well-known analytical approximations, determining in that way their validity in all kinematical regions and showing to what extent accounting for multiple scatterings is crucial...
Jet modification is a multi-stage (multi-scale) process: an initial high virtuality stage gives way to a lower virtuality transport stage for high energy partons, and a strongly coupled phase for lower energy parts of the shower. The transition from the high virtuality medium-modified DGLAP stage takes place when the virtuality reaches the medium induced scale 𝑞̂ 𝜏, where 𝜏 is the lifetime of...
The lepton pair production in ultraperipheral collisions is studied in the classical field approximation. We derive a general form of the cross section in terms of photon distributions that depend on the transverse momentum and coordinate based on the wave packet form of nuclear wave functions. Such a general form of the cross section in the classical field approximation contains the results...
Direct photons are a useful probe to study the properties of QGP and the dynamic evolution of the collision system as they do not interact with the medium strongly. Low transverse momentum direct photons are believed to originate primarily from thermal radiation, however, calculations of thermal photon emission fall short in describing the measured direct photon yield and the anisotropy at the...
Quantum Chromodynamics (QCD), the theory of strong interactions, predicts that at sufficiently high temperature and/or high energy density normal nuclear matter converts into a deconfined state of quarks and gluons, known as the Quark-Gluon Plasma (QGP). To investigate the phase diagram of QCD matter, the Relativistic Heavy Ion Collider (RHIC) started the first phase of the Beam Energy Scan...
The search for the Quantum Chromodynamics (QCD) critical point is underway at the Relativistic Heavy-Ion Collider (RHIC) Beam Energy Scan II. The primary signature of the critical point is a peak (divergence) in the kurtosis of the net-proton number distribution, $\kappa_4$. Most previous studies of kurtosis have focused on equilibrium physics, whereas it is well-known that out-of-equilibrium...
The injection of energy and momentum from a jet into the QGP generates a wake, which leads to soft and semi-hard particle creation correlated with the jet direction after the QGP hadronizes. As several jet quenching studies have shown, this medium response phenomenon plays a crucial role in our understanding of many jet structure and substructure observables. Nevertheless, a detailed account...
The temperature and size of the quark-gluon plasma that is created in heavy-ion collisions are properties that are to be experimentally constrained. This can be done via direct photon Hanbury Brown and Twiss (HBT) measurements that are able to both quantify the excess of thermal photons as well as the size of the emitting source. In contrast to femtoscopic measurements of bulk particles, this...
We probe the origin of strangeness enhancement by separating the strange particles produced in hard processes (jets) from those produced in soft processes (bulk) using the measurement of triggered hadron-$\phi$(1020) and hadron-$\Lambda$ angular correlations. Separating these measurements by event muliplicity in p-Pb collisions allows one to measure the effects of increasing system size on...
Electrons constitute an essential component of final states from the leptonic decay channels of W and Z bosons. Their reconstruction and identification are especially challenging in heavy-ion collisions due to high detector occupancy. Therefore, the evaluation of electron performance is crucial for precision measurements of properties of quark-gluon plasma produced in heavy-ion collisions at...
The study of nucleon-nucleon (N-N), nucleon-hyperon (N-Y), and hyperon-hyperon (Y-Y) interactions are fundamental to understanding the physics of relativistic heavy-ion collisions and neutron stars the existence of various exotic hadrons. Geometry and dynamics of the particle-emitting source in heavy-ion collisions can be inferred via the femtoscopy method. Two-particle correlations at small...
Near perfect fluid behavior is a hallmark signature of the quark gluon plasma (QGP), however, how this behavior emerges is still not fully understood. Thus, measurements of many different particles over a wide rapidity range are needed to understand this phenomenon. Heavy quark flow is expected to be different from light quark flow due to their larger masses, making heavy flavor flow...
We present the latest predictions for several QCD processes at low-x in the color dipole picture which are of interest for current hadron-hadron and future electron-hadron colliders. The predictions are derived using the solution to the Balitsky-Kovchegov equation for proton and nuclear targets with the collinearly improved kernel and including the impact-parameter dependence. Two different...
Ultra-relativistic collisions of small nuclear systems can shed light on the onset of QGP formation. So far, proton-nucleus (p+A) and deuteron-nucleus (d+A) collisions have been used to study the emergence of the smallest QGP droplets, producing the puzzling results that the non-zero elliptic flow of hadrons at intermediate transverse momenta is not correlated to the suppression of their...
Partonic jets, i.e. highly energetic collimated sprays of strongly interacting particles, provide an excellent means to study the hot and dense medium
of a quark gluon plasma (QGP), since the highly energetic jet particles interact with the medium particles, however do not thermalize.
Jet particles in the medium undergo both processes of scatterings off medium particles as well as emission...
We have derived the chiral kinetic theory (CKT) with collisions in a QED matter. We have discussed the global equilibrium conditions in the presence of collisions. Then, we implement the CKT with effective collision term in the moment expansion and derive the off-equilibrium corrections to the axial currents and spin polarization vector.
Bulk matter produced in heavy ion collisions has multiple
conserved quantum numbers like baryon number, strangeness and electric charge. The diffusion process
of these charges can be described by a diffusion matrix describing the interdependence of diffusion of
different charges. The diffusion coefficient matrix is estimated here from the Boltzmann kinetic theory
for the hadronic phase...
We present a consistent photon production calculation from hadronic cross sections, including bremsstrahlung and 2-to-2 reactions, matching the usually employed thermal rates [1]. Using the hadronic transport approach SMASH as the afterburner for the hadronic stage at RHIC and LHC energies, we find a significant increase in the calculated momentum anisotropies of these photons due to...
We present, for the first time at LHC energies, the forward rapidity gap spectra from proton-lead collisions for both pomeron-lead and pomeron-proton topologies. The analysis is performed over 10.4 units of pseudorapidity at a nucleon-nucleon center-of-mass energy of 8.16 TeV, i.e. almost 300 times higher than previous measurements of diffractive production in proton-nucleus collisions. For...
The primary goal of the ultrarelativistic heavy-ion collision program at the LHC is to recreate the quark-gluon plasma (QGP) and study its properties. However, the lack of knowledge on the initial conditions of heavy-ion collision results in a significant uncertainty of the extraction of the transport properties of QGP. Recently, it has been realized that the generation of transverse momentum...
Central and mid-peripheral heavy-ion collisions produce a significant underlying event superimposed on the hard scattering of interest. So far, traditional underlying event mitigation algorithms introduced for heavy-ion often impose limitations in their applicability. The jet typically has to be clustered in the presence of the underlying event. Observables like the energy have to be corrected...
In the RHIC Beam Energy Scan program, gold nuclei are collided with different collision energies in the range from few to 62.4 GeV. The goals of the program are to explore the onset of QGP creation, locate the critical point of QCD and study dense baryon matter.
In this talk, we report on the first application of 3D Monte Carlo Glauber (GLISSANDO2) and TrENTO p=0 initial states for 3D...
In heavy-ion collisions, the highly relativistic ions act as a strong source of electromagnetic radiation, enhanced by the large proton charge number $Z$. Ultra-peripheral collisions (UPC) offer a natural environment in which to observe the photon-initiated production of Beyond Standard Model (BSM) processes with QED couplings. One such process sensitive to BSM effects is light-by-light...
We compute the spectrum of dileptons produced by the quark-gluon plasma in the intermediate mass range 1<M<5 GeV using state-of-the-art QCD kinetic theory. Our calculation takes into account the anisotropy of the quark and gluon momentum distributions at early times, as well as the underpopulation of quarks relative to gluons. The resulting dilepton spectrum satisfies approximate transverse...
Understanding the impact of strong magnetic fields on QCD dynamics is important for an accurate description of non-central heavy-ion collisions and neutron stars. Lattice simulations found that a finite magnetic field affects the chiral dynamics of QCD in a non-trivial way. At low temperatures, the magnitude of chiral condensate increases with the magnetic field, the phenomenon known as the...
In high-energy heavy-ion collisions, strong and transient electromagnetic fields (~$10^{14}~[\rm{T}]$) are induced inside generated hot and dense QCD medium.
The space-time evolution of the electromagnetic field in electrically conducting nuclear matter is completely different from that of vacuum; the lifetime of it becomes much longer than that in the vacuum. Also, the electrical...
Measurements of jet profiles in high-energy collisions are sensitive probes of QCD parton splitting and showering. Precise understanding of the jet structures are essential for setting the baseline not only for nuclear modification of jets in heavy-ion collisions, but also for possible semi-soft cold QCD effects such as multi-parton interactions (MPI) that may modify jets in high-multiplicity...
Recently observed signs of collectivity in small systems has highlighted the need for a better understanding of equilibration in small and large collisions systems. In search of this, the QCD effective kinetic theory formulated by Arnold, Moore and Yaffe (AMY) [1] has emerged as a promising candidate. In order to bridge the gap between theory and experiments we develop a parton cascade that...
Directed and elliptic flow have been extensively studied in heavy-ion collisions while triangular flow ($v_3$) could be further explored. $v_3$ could prove very useful as a signal for Quark-Gluon Plasma (QGP) formation due to its link to viscosity and the possibility that it is less affected by transport dynamics at very low energies [1]. This poster presents the current progress of an...
Modern models for describing heavy-ion collisions have difficulty reproducing observed flow in very central collisions -- a problem known as the ultra-central flow puzzle. It is therefore useful to understand what properties the initial stages must have in order to be compatible with experimental data. To this end, we parameterize the early-time energy density and its fluctuations via its...
We present a systematic study of $\Lambda$ hyperon polarization in heavy-ion collisions at HADES energies within the framework of microscopic transport model UrQMD combined with the hadron-resonance gas statistical model. This study demands a complex analysis of the fireball evolution including time slices, extraction of temperature and baryonic chemical potentials, as well as freeze-out...
In the EKRT model for ultrarelativistic heavy-ion collisions, we compute the initial fluctuating QCD-matter energy densities from NLO pQCD and saturation, and describe the subsequent space-time evolution of the system with dissipative fluid dynamics, event by event [1,2,3]. This model agrees remarkably well with the low-$p_T$ flow observables measured in Pb+Pb and Xe+Xe collisions at the LHC,...
We study nonperturbative flavor correlations between pairs of leading and next- to-leading charged hadrons within jets and their modifications in the presence of a QCD medium. A charge correlation ratio observable $r_{c}$, generalized from the balance function [1] which distinguishes between same-sign and opposite-sign charged pairs, is introduced. This observable $r_c$ is studied as a...
Color Glass Condensate (CGC) effective field theory (EFT) at leading order describes well the Deep Inelastic Scattering (DIS) inclusive cross section data at small-x as measured by the HERA experiments [1-3]. Recently the inclusive DIS impact factors have been calculated in Next-to-Leading Order (NLO) accuracy in CGC EFT [4-6], and the soft gluon divergence present at NLO has been factorized...
An ultra-intense magnetic field is expected to be created in relativistic heavy-ion collisions with an intensity up to 10$^{15}$ T. These strong magnetic fields are predicted to produce various nonlinear QED behaviors and other interesting phenomena, such as the chiral magnetic effect and quark synchrotron radiation. However, such a magnetic field has not yet been detected experimentally. The...
The LHCb detector is a single-arm forward spectrometer covering the pseudorapidity range 2 < 𝜂 < 5, designed for the study of particles containing bottom or charm quark. The study of exclusive vector meson photoproduction in ultra-peripheral lead-lead collisions is essential to understand physics at low Bjorken x. In particular, coherent J/ψ and ψ(2S) mesons are promising probes of nuclear...
In the recent decades of high energy physics, it was revealed that in ultra-realistic ion-ion collisions, a strongly interacting quark-gluon plasma (sQGP) is created. One of the most important goals of NA61/SHINE is to investigate and understand the phase structures of this matter. The investigation of the phase-diagram can be achieved by varying the collision energy or by changing the...
The sPHENIX detector at the Relativistic Heavy Ion Collider is designed to measure high momentum probes of the quark-gluon plasma such as jets. Jet measurements in heavy-ion collisions require subtraction of the large underlying event consisting of low momentum particles produced from the QGP medium. While subtraction techniques can remove the average size of the background, localized...
In this talk, we analyze the factorization ratio $r_n(\eta_p^a,\eta_p^b)$ in Xe+Xe and Pb+Pb collisions [1] using event-shape engineering within the integrated dynamical model [2,3] constructed of the Monte-Carlo Glauber model for the initialization, rfh for 3+1D relativistic fluctuating hydrodynamics with hydrodynamic fluctuations [2], and JAM for hadronic cascades [4]. We also address...
The search for the QCD critical point is one of the main topics in high-energy nuclear collisions. There are active studies aiming to find signals of the QCD critical point and the first order phase transition, such as the BES programs at the Relativistic Heavy-Ion Collier (RHIC), and many future experiments such as FAIR, NICA, J-PARC-HI, and HIAF. For detecting the signals of the critical...
Hadronic resonances can act as useful probes to examine the hadronic phase in ultra-relativistic heavy-ion collisions. On the other hand, there could also be perspectives and unexplored methods for studying the partonic phase via resonances. Properties, such as the masses and widths, of resonances produced or decaying during the partonic phase could be modified.
In order to reach resonances...
We employ machine learning techniques to identify important features that distinguish jets produced in heavy-ion collisions from jets produced in proton-proton collisions [1]. We formulate the problem using binary classification and focus on leveraging machine learning in ways that inform theoretical calculations of jet modification: (i) we quantify the information content in terms of Infrared...
The thermal fit to preliminary HADES data of Au+Au collisions at $\sqrt{s_{_{NN}}}=2.4$ GeV shows two degenerate solutions at $T\approx 50$ MeV and $T\approx 70$ MeV. The analysis of the same particle yields in a transport simulation of the UrQMD model yields the same features, i.e. two distinct temperatures for the chemical freeze-out. While both solutions yield the same number of hadrons...
Fluid dynamic considerations are used to determine the electric current spectral density in the regime of small energies and momenta. The spectral density in this regime is parameterized by the electric conductivity, the charge susceptibility, and the relaxation time for the electric current, which is needed for relativistic causality. Experimentally, the spectral function can be accessed...
Nuclei with equal number of baryons but varying proton number (isobars) have many commonalities, but differ in both electric charge and nuclear structure. Relativistic collisions of such isobars provide unique opportunities to study the variation of the magnetic field, provided the nuclear structure is well understood. In this Letter we simulate collisions using several state-of-the-art...
Two-particle normalized cumulants of particle number correlations ($R_{2}$) and transverse momentum correlations ($P_{2}$) measured as a function of relative pseudorapidity and azimuthal angle difference $(\Delta\eta, \Delta\varphi)$ provide key information about particle production mechanism, diffusivity, charge and momentum conservation in high-energy collisions. To complement the recent...
Experimental data on a wide range of jet observables measured in heavy-ion collisions provide strong constraints on the underlying medium dynamics and are addressed by state-of-the-art Monte Carlo models. However, so far there has been little theoretical guidance on the systematics of medium modifications on such diverse quantities as the inclusive jet spectrum, the intra-jet fragmentation...
Scaling phenomena, and the associated self-similar evolution, play an important role in characterizing the off-equilibrium evolution of many physical systems. In far-from-equilibrium QCD, the distribution functions of quarks and gluons have been found to have self-similar evolution in terms of a scaling function and scaling exponents [1,2,3]. In this work [4] we use the collision kernel for...
A recent analysis from the PHENIX collaboration on direct photon production yield in heavy ion collisions has shown a universal, within experimental uncertainties, multiplicity scaling, in which the photon $p_T$-spectra for transverse momenta up to 2 GeV/c are scaled with charged-hadron pseudorapidity density at midrapidity raised to the power $\alpha=1.25$. This low-$p_T$ scaling suggests...
We have extended the so-called QCD colour re-connection model with spatial constraints on the allowed re-connection between the colour strings in the Pythia8/Angantyr model. The Angantyr model uses the Pythia8 event generator machinery with sophisticated stacking of pp-like collisions to simulate heavy-ion events, without any assumption of a thermalized medium of QGP. So far, all...
The PHENIX experiment was operated at BNL-RHIC which collides heavy ions at
relativistic energy to create a quark-gluon plasma (QGP), in which quarks and gluons are deconfined. It is well known that the QGP produced in heavy ion collisions exhibits collective motion. In recent years, similar collective effect have been discovered in small systems at high energy collisions. This result...
QCD vacuum fluctuations can lead to chirality anomaly and parity violation in metastable local domains. This would result in a charge separation along the strong magnetic field produced in off-center relativistic heavy-ion collisons, a phenomenon called the chiral magnetic effect (CME). A widely used observable to search for the CME is the charge-dependent three-point correlator,...
A new complete method, based on the Wigner distributions of photons, how to calculate differential distributions of dileptons created via photon-photon fusion in semicentral ($b<2R_{AA}$) AA collisions is reviewed [1]. The formalism is used to calculate different distributions of invariant mass, dilepton transverse momentum and acoplanarity for different regions of centrality. The results of...
Motivated by the quark-gluon plasma, we develop a simulation method to obtain the spectral function of fermions non-perturbatively in a non-Abelian gauge theory with large gluon occupation numbers. We apply our method to a non-Abelian plasma close to a far-from-equilibrium self-similar regime, and find very good agreement with perturbative hard loop (HTL) calculations for medium-induced...
Trento-3D is a parametric initial condition model, specifically designed for rapidly generating 3D energy distributions to initialize fully (3+1)-dimensional, event-by-event hydrodynamic simulations of ultrarelativistic heavy-ion collisions. Trento-3D builds upon the well-established T${}_\mathrm{R}$ENTo model [1], which samples nuclear configuration with subnucleonic structure and determines...
Heavy-ion collisions has 3 relevant conserved charges: baryon number (B), strangeness (S), and electric charge (Q). We have developed a new 2+1 relativistic viscous hydrodynamic code using Smoothed Particle Hydrodynamics that conserves BSQ, coupled to a 4D Lattice Quantum Chromodynamics equation of state. ICCING initial conditions that account for gluon splittings into quark anti-quark pairs...
Photonuclear collisions are one of the simplest processes that can happen in a heavy-ion collision. They occur when one nucleus emits a quasi-real photon which interacts with the other colliding nucleus, similar to an $e+A$ collision except that the photon tends to have a much smaller virtuality. Photonuclear collisions can be used to study bulk properties of the medium such as collectivity...
Mini-jets, created by perturbative hard QCD collisions at moderate energies, can represent a significant portion of the total multiplicity of a heavy-ion collision event. Given the fact that their transverse momenta are initially larger than the typical saturation scale describing the bulk of the equilibrating QGP, they ought to be described through the physics of parton energy loss. Indeed,...
We study jet momentum broadening in heavy ion collisions at initial stages. We focus on the jet quenching parameter $\hat q$, which we extract using effective kinetic theory. We obtain its non-equilibrium properties during the initial stages in a Bjorken-expanding plasma with non-thermal anisotropic initial conditions.
Recent measurements on $\Lambda$ hyperon's polarization suggest a strong correlation with the local fluid vorticity in hydrodynamic models. Jet-medium interactions induce a generic vortex ring structure of the fluid kinematic vorticity along the quenched jet axis. In this talk, we propose a novel ring observable R^J to capture such a ring excitation in the fluid's flow field by high-energy...
Extraction of the Quark-Gluon Plasma (QGP) transport properties (i.e. specific shear viscosity $\eta/s$) is a prime goal of the heavy-ion programs at the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC). Correlators that are sensitive to both initial-state effects and final-state viscous attenuation can give invaluable constraints for temperature ($T$) and chemical...
Measurements of reconstructed jets and jet substructure offer opportunities to study fragmentation in a nuclear environment. Jet measurements in $p$+A collisions can provide crucial information for understanding the relationship between hard and soft processes in small collision systems. However, at RHIC this promise is complicated by the low jet energies and lack of hadronic calorimetry in...
Fluctuations of conserved charges, in particular the baryon number fluctuations, are thought of as experimental observables which are sensitive to the QCD critical end point (CEP), where the singular part of thermodynamic functions plays a dominant role. Indeed, in the past several years significant fluctuation measurements have been performed in the Beam Energy Scan program at RHIC, and an...
Dielectron production in high-multiplicity pp collisions at $\sqrt{s}$ = 13 TeV with ALICE
Dielectron production is a powerful tool to investigate the properties of the quark-gluon plasma created in relativistic heavy-ion collisions, as they carry information about the temperature of the medium and its space-time evolution without any distortion due to final-state interactions. Dielectron...
Jet substructure is a powerful tool to probe the perturbative regime of jet evolution in proton-proton and heavy-ion collisions. Over the past few years, a wide variety of substructure observables have been proposed in order to understand specific aspects of jet dynamics in a quark-gluon plasma (QGP).
In this talk, based on [1], we will explore the ability of such an observable, called...
We analyze the behavior of cumulants of conserved charges in a subvolume of a thermal system with exact global conservation laws by extending [1] a recently developed [2] subensemble acceptance method (SAM) to multiple conserved charges. Explicit expressions for all diagonal and off-diagonal cumulants up to sixth order that relate them to the grand canonical susceptibilities are obtained. The...
I will discuss recent work that aims to understand the initial state of the fragmentation region of heavy ion collisions using an entirely classical framework that incorporates the phenomenon of gluon saturation. The first step in the program, recently carried out by Kajantie, McLerran, and Paatelainen, is to study the gluon radiation from a classical point particle struck by a sheet of...
We present result on an anisotropic transverse flow of kaons ($K^+$, $K^0_S$ and $K^-$) in Au+Au collisions at $\sqrt{s_\mathrm{NN}} = 2.42\,\mathrm{GeV}$ measured with HADES. It was proposed already in mid-nineties that kaon flow around its production threshold might be a good probe for kaon-nucleon potential, and consequently for nuclear equation-of-state [1]. The presented analysis was...
We present a systematic study of the hyperon global polarization's sensitivity to the collision systems' initial longitudinal flow velocity, by extending our previous work [1] to event-by-event 3+1D hydrodynamic simulations. By explicitly imposing local energy-momentum conservation when mapping the initial collision geometry to macroscopic hydrodynamic fields, the evolution of systems' orbital...
Since 2011 a wide variety of measurements suggest the existence of strong collectivity in collisions of small systems such as proton-proton (pp) and proton-nucleus (pPb) with hydrodynamic models and gluon saturation in the initial state as two theory alternatives showing consistency with the observations. These results raise the question as to whether such phenomena may be present in even...
Two particle correlation analysis is often used to study the spatial and temporal extents of particle emitting source in high-energy nuclear collisions. By studying the quantum statistical effects (QS) and final state interactions (FSI) between two particles, one can extract emission source parameters used to describe the geometrical and dynamical properties of the homogeneity region....
Angular correlations of identified particles measured in ultrarelativistic proton-proton (pp) and heavy-ion collisions exhibit a number of features which depend on the collision system and particle type under consideration. Those features are produced by mechanisms, such as (mini)jets, elliptic flow, resonance decays, and conservation laws. In addition, of particular importance are those...
A multi-phase transport (AMPT) model has been successful in reproducing a wide range of observables in relativistic heavy-ion collisions. However, certain key parameters need to have significantly different values for pp and central AA collisions for the model to well describe the yield and transverse momentum spectrum of the bulk matter.
In this work[1], we extensively study the system...
In this contribution the nuclear modification factor ($R_\mathrm{AA}$) of prompt charm hadrons and heavy-flavour hadrons decaying to leptons measured in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV by the ALICE Collaboration are presented. The measurement of heavy-flavour leptons in Xe-Xe collisions is also discussed. Heavy quarks are a very suitable probe to investigate the quark-gluon...
Charge-dependent azimuthal anisotropy Fourier coefficients are measured with two- and three-particle correlations in pPb and PbPb collisions. The difference between positively and negatively charged particles for the second-order two-particle $(v_2\{2\})$ and three-particle $(v_2\{3\})$ coefficients for both pPb and PbPb, and third order two-particle coefficient $(v_3\{2\})$ for PbPb, are...
Particle flow measurements, which provide evidence of the QGP medium, are a powerful tool to study the QGP evolution in heavy-ion collisions. Using the two-particle correlation technique, LHCb has observed the ridge structure due to particle flow, in the forward pseudorapidity range $2<\eta<5$ alongside the leading jet peak in long-range correlations ($|\eta|>2$). This talk will detail the...
Ultraperipheral lead-lead collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV produce very large photon fluxes that provide the conditions to study photon-photon fusion processes in phase space regions inaccessible with proton-proton data. Measurements of light-by-light (LbyL) scattering and lepton pair photoproduction in ultraperipheral PbPb collisions will be presented with data collected...
Photon-photon and photonuclear reactions are induced by the strong electromagnetic field generated by ultrarelativistic heavy-ion collisions. These processes have been extensively studied in ultra-peripheral collisions with impact parameters larger than twice the nuclear radius. Since a few years, both the photoproduction of the J/$\psi$ vector meson and the production of dileptons via...
We derive a semi-classical kinetic theory for massive spin-1 particles from the Wigner-function formalism.
Starting from an interacting Proca Lagrangian, we obtain equations of motion for the Wigner function of massive charged vector bosons in classical electromagnetic fields. Performing a power-expansion up to first order in the Planck constant $\hbar$, we then derive generalized...
This talk presents a new measurement of longitudinal decorrelation in $pp$ collisions with ATLAS. It is expected that the deposited energy in the transverse ($x,y$) plane varies, depending on the longitudinal ($z$) slice examined, which is correlated with the rapidity of the produced particles. Thus, particles from different rapidity slices will have flow vectors that differ in magnitude...
Open heavy-flavor hadron production, azimuthal anisotropy and correlations in heavy-ion collisions serve as powerful tools to study quark-gluon plasma (QGP) properties, heavy-flavor energy loss due to interaction with QGP, and heavy-flavor hadronization.
This talk presents recent ATLAS results on the azimuthal anisotropy ($v_2$ and $v_3$) and nuclear modification factor ($R_\mathrm{AA}$),...
The quark-gluon plasma (QGP) is a fluid at a long wavelength and becomes a collection of weakly-coupled partons at an asymptotically short wavelength. However, its properties at the "mesoscopic" length scale, which is too short for a fluid description and too long for a perturbative treatment, remain elusive. In this work, we consider the response of QCD-like plasma to energy/momentum...
Because of the different binding energies, bottomonium mesons are particularly useful probes to understand the thermal properties of quark-gluon plasma. Previously, CMS observed the sequential suppression of $\Upsilon$(1S), $\Upsilon$(2S), and $\Upsilon$(3S) in heavy ion (AA) collisions, which was widely accepted as evidence for the QGP formation. However, the $\Upsilon$(3S) yield was...
The collective flow of particles, generated in the expansion of the dense matter that is created in heavy-ion collisions, fluctuates from event to event. In particular, the flow vectors at two different transverse momenta fluctuate with respect to each other. One way to probe this flow fluctuation is to study the decorrelation between the flow at two different momentum bins. However, the...
Measurements of quarkonia production in peripheral and ultra-peripheral heavy-ion collisions are sensitive to photon-photon and photon-nucleus interactions, the partonic structure of nuclei, and the mechanisms of vector-meson production. LHCb has studied both coherent and incoherent production of $J/\psi$ mesons in peripheral and ultra-peripheral collisions using PbPb data at forward rapidity...
In heavy-ion collisions, the observation of the global hyperon polarization, $\overline{P}_\mathrm{H}$, ranging from $\sqrt{s_\mathrm{NN}}=7.7$~GeV to 5.02~TeV has revealed the existence of large vorticities perpendicular to the reaction plane due to system's orbital angular momentum. We present recent results on $\overline{P}_\mathrm{H}$, and differential measurements thereof, extended to the...
Relativistic heavy-ion beams are accompanied by a large flux of equivalent photons, giving rise to a set of photon-induced processes. These can lead to photon-photon interactions in ultraperipheral collisions. This talk presents a series of measurements of such processes performed by the ATLAS Collaboration. New measurements of exclusive dilepton production (electron, muon, or tau pairs) are...
The recently discovered abundance of hadrons with more than three valence quarks remains poorly understood. Measurements of these exotic hadrons and their interactions with the QCD medium provides a new avenue to investigate their properties. Additionally, the production of hadrons with more than three quarks presents new testing grounds for models of particle transport and recombination in...
Ultra-strong electromagnetic field can generate a large flux of quasi-real photons arising from the Lorentz-contraction and the large electric charge (Z) of heavy nuclei colliding at ultra-relativistic speeds. These ultra-strong fields can be studied through dileptons ($e^{+}e^{-}$ and $\mu^{+}\mu^{-}$) and vector mesons ($J/\psi$) produced via photon-photon and photonuclear processes,...
Quantum Chromodynamics allows for the formation of parity-odd domains inside the medium produced in heavy-ion collisions associated with a net chirality of the quarks. As a consequence, the Chiral Magnetic Effect (CME) and Chiral Vortical Effect (CVE) are phenomena predicted to occur and cause electric-charge and baryonic-charge separation along the direction of the magnetic field and...
Heavy quarks are one of the most important probes to study the properties of quark-gluon plasma (QGP). Hadronization of beauty quarks is not as well understood as in the charm sector. Illuminating the hadronization mechanism is crucial for extracting the transport properties of the QGP. We present new results on nuclear modification factors of $B^0_s$ and $B^+$ mesons and their yield ratios in...
In this contribution, we present the latest measurements of $\mathrm{D}^0$, $\mathrm{D}^+$ and $\mathrm{D_s}^+$ mesons together with the final measurements of $\Lambda_\mathrm{c}^+$, $\Xi_\mathrm{c}^{0,+}$, $\Sigma_\mathrm{c}^{0,++}$, and the first measurement of $\Omega_\mathrm{c}^0$ baryons performed with the ALICE detector at midrapidity in pp collisions at $\sqrt{s}=5.02$ and $\sqrt{s}=13$...
A challenging goal in relativistic heavy-ion physics is the
investigation of the phase diagram of strongly interacting matter and
the determination of its phase structure, governed by the approximate
chiral symmetry of the light-quark sector of QCD. In this study [1] we
investigate a linear quark-meson $\sigma$ model in and out of
equilibrium employing Schwinger-Keldysh real-time...
With a unique geometry covering the forward rapidity region, the LHCb detector provides unprecedented kinematic coverage at low Bjorken-$x$ down to $x \sim 10^{-5}$ or lower. The excellent momentum resolution, vertex reconstruction and particle identification allow precision measurements down to very low hadron transverse momentum. In this contribution, we present the latest studies of the...
The diffractive photoproduction of $\rm{J/\psi}$ vector mesons is studied at the LHC with the ALICE detector in p--Pb and Pb--Pb ultra-peripheral collisions (UPCs), where the Pb ions act as powerful sources of quasi-real photons.
In this talk, the first measurement at the LHC of dissociative photoproduction of $\rm{J/\psi}$ off protons is presented; this process is sensitive to quantum...
In this presentation, I'll introduce the effective viscosity that can be computed from the viscous damping of anisotropic flow in heavy-ion collisions for arbitrary temperature-dependent shear and bulk viscosities, running ideal and viscous hydrodynamic simulations. I'll show that the damping is solely determined by effective shear and bulk viscosities, which are weighted averages over the...
Being a powerful probe of the quark-gluon plasma (QGP), charm quarks have been widely studied in heavy-ion collisions. They have provided unique insights into the parton energy loss and the degree of thermalization in the hot medium, but an inadequate knowledge of the hadronization processes has hampered the interpretation of experimental results. In heavy-ion collisions, charm hadron...
Measurements of bottomonium states in heavy-ion collisions provide a powerful tool to study both initial-state effects on heavy-quark production and final-state interactions between heavy quarks and the quark-gluon plasma (QGP).
The ATLAS experiment at LHC has measured the production of bottomonium states $\Upsilon$(1S), $\Upsilon$(2S) and $\Upsilon$(3S), in Pb+Pb and $pp$ collisions at a...
We explore the far-from-equilibrium dynamics of a (0+1)-dimensionally expanding system of massive particles with Bjorken symmetry using kinetic theory and hydrodynamics. By comparing the decay of various initializations on the attractor in both frameworks, we test the effectiveness of hydrodynamics in providing an accurate description of the underlying kinetic theory in far-off-equilibrium...
One important challenge in our field is to understand the initial condition of the QGP and constrain it using sensitive experimental observables. Recent studies show that the Pearson Correlation Coefficient (PCC) between $v_n$ and event-wise mean transverse momentum $[p_\mathrm{T}]$, $\rho_n(v_n, [p_\mathrm{T}])$, and its centrality dependence can probe several ingredients of the initial...
The exclusive photoproduction of vector mesons provides a unique opportunity to constrain the gluon distribution function within protons and nuclei. Measuring vector mesons of various masses over a wide range of rapidity and as a function of transverse momentum provides important information on the evolution of the gluon distribution within nuclei. A variety of measurements, including the...
Partons (quarks/gluons) in heavy-ion collisions interact strongly with the Quark-Gluon Plasma (QGP), and hence have their energy and shower structure modified compared to those in vacuum, e.g., those produced in proton-proton collisions. Theoretical calculations predict that radiative energy loss, which is the dominant mode of energy loss for gluons and light quarks in the QGP, is suppressed...
This talk reports the observation of $\tau$-lepton pair production in ultraperipheral lead-lead collisions and a measurements of for the $\tau$-lepton anomalous magnetic moment, $a_{\tau}$. The dataset corresponds to an integrated luminosity of 1.44/nb of Pb+Pb collisions at 5.02 TeV recorded by the ATLAS experiment in 2018.
Femtoscopic correlations of identified and unidentified hadrons are measured with data re-corded by the CMS experiment at the LHC over a broad multiplicity range and pair transverse momentum. The first femtoscopy measurements carried in CMS for all pair combinations of $\mathrm{K}^{0}_{\mathrm{S}}$, $\Lambda$ and $\overline{\Lambda}$ are reported. These identified particles are employed to...
We discuss the sensitivity of the process in ultraperipheral Pb+Pb collisions on the anomalous magnetic ($a_\tau$) and electric ($d_\tau$) moments of $\tau$ lepton at LHC energies. We derive the corresponding cross sections by folding the elementary cross section with the heavy-ion photon fluxes and considering semi-leptonic decays of both $\tau$ leptons in the fiducial volume of ATLAS and CMS...
In recent years, a significant theoretical effort has been made towards a dynamical description of quarkonia inside the Quark-Gluon Plasma (QGP), using the open quantum systems formalism. In this framework, one can get a real-time description of a quantum system (here the quarkonium) in interaction with a thermal bath (the QGP) by integrating out the bath degrees of freedom and studying the...
Parton showers lie at the core of general purpose Monte Carlo event generators. They aim at correctly describing the phase-space for QCD branchings across disparate energy scales. A natural question, largely overlooked in the literature, is up to which degree of logarithmic accuracy do parton showers meet this goal. In this talk, I’ll present a new class of dipole showers for hadronic...
The main goal of ultrarelativistic heavy-ion collisions is to create a new state of matter called quark-gluon plasma (QGP) and study its properties. One of the dominant uncertainties present in such a study originates from poorly constrained initial conditions. In this talk, we present the final results of anisotropic flow measurements with high-order cumulants for inclusive and identified...
Collisional broadening in QCD plasmas leads to the emission of medium induced radiation, which governs the energy loss of highly energetic particles or jets. While recent studies have obtained non-perturbative contributions to the collisional broadening kernel $C(b_{\bot})$ using lattice simulation of the dimensionally reduced long-distance effective theory of QCD, Electrostatic QCD (EQCD)...
Measurements of the correlations of the final-state heavy flavor hadrons are of great interest since they provide information about the initial collision geometry and its fluctuation. More importantly, those measurements could reveal the mass dependence of parton energy loss and quark diffusion in the Quark-Gluon Plasma (QGP). In this talk, we report the first measurement of the azimuthal...
Charmonium production is a direct probe of deconfinement in heavy-ion collisions. For J/$\psi$, a bound state of ${c}\bar{c}$ quarks, its (re-)generation within the QGP or at the phase boundary, is found to be the dominant production mechanism at low transverse momentum ($p_{\rm T}$) and in central Pb–Pb collisions at the LHC energies. The relative production of the $\psi$(2S) excited state...
Hadrons are elementary excitations of the QCD vacuum, and their properties reflect the state of the vacuum. The properties of the vacuum are theoretically suggested to be modified at finite density or temperature. Therefore, measuring hadrons under such an environment will lead to understanding of the property of QCD vacuum.
The J-PARC E16 experiment focuses on a measurement of the spectral...
Measurements of direct photons can provide valuable information on the properties and dynamics of the quark-gluon plasma (QGP) by comparing them to model calculations that describe the whole evolution of the system created in heavy-ion collisions, from the initial conditions to the pre-equilibrium, QGP, and hadronic phases.
In the ALICE experiment, photons can be reconstructed either by using...
The collective behavior of \ensuremath{\mathrm{K^0_S}} and \ensuremath{\Lambda}/\ensuremath{\bar{\Lambda}} strange hadrons is studied using the scalar-product and multiparticle correlation methods. Proton-lead (pPb) collisions at the nucleon-nucleon center-of-mass energy $\sqrt{s_{\mathrm{NN}}} =$ 8.16 TeV and lead-lead (PbPb) collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV are...
Charm and bottom quark production is an important experimental observable that sheds light on the heavy quark interaction with the nuclear medium. With high statistics datasets, tracking and PID at very low transverse momentum, and
excellent vertexing capabilities, LHCb performs precision measurements of a rich set of heavy flavor hadrons, including B mesons, open charm hadrons and...
We present the first combination of light-by-light scattering ($\gamma\gamma\rightarrow \gamma\gamma$) cross-section measurements at LHC, using lead-lead data recorded by the ATLAS and CMS Collaborations at $5.02\,\text{TeV}$ and corresponding to integrated luminosities of 2.2 and $0.39\,\text{nb}^{-1}$, respectively. The combined cross-section is $115\pm 19\,\text{nb}$, with the two...
The high-$\mu_{\rm B}$ region of the QCD phase diagram has become the object of several studies, focused on the investigation of the order of the phase transition and the search for the critical point. Accessing rare probes, which include electromagnetic observables and heavy quark production, is experimentally challenging as it requires large integrated luminosities, and a fixed-target...
Searches for the onset of deconfinement are one of the main motivations of the Beam Energy Scan (BES) program at RHIC. Strangeness production has been suggested as a sensitive probe to the early-time dynamics of the deconfined matter, due to their small hadronic interaction cross section, early freezeout from the medium and short lifetime for some resonances, e.g. $K^{*0}$. The BES Phase I...
The LHCb spectrometer has the unique capability to function as a fixed-target experiment by injecting gas into the LHC beampipe while proton or ion beams are circulating. The resulting beam+gas collisions cover an unexplored energy range that is above previous fixed-target experiments, but below the top RHIC energy for AA collisions. Here we present new results on antiproton and charm...
In this work, the qualitative impact of the net baryochemical potential dependence of the shear viscosity to entropy density ratio $\eta/s$ in hydrodynamical simulations is studied. The effect of a predicted non-constant $\eta/s(\mu_B)$ is largely unexplored in hydrodynamic simulations. Previous studies focus only on a temperature dependence[1-3] or even only a constant effective shear...
Electromagnetic probes such as photons and dielectrons are a unique tool to study the space-time evolution of the hot and dense matter created in ultra-relativistic heavy-ion collisions. They are produced by a variety of processes during all stages of the collision with negligible final-state interactions. At low dielectron invariant mass ($m_{\rm ee}$), thermal radiation from the hot hadron...
The Compact Muon Solenoid (CMS) detector at the CERN Large Hadron Collider (LHC) will undergo an extensive Phase II upgrade program to prepare for the more challenging conditions of the High-Luminosity LHC (HL-LHC) in the high energy particle and nuclear physics program. A new time-of-flight layer is designed to measure minimum ionizing particles (MIPs) with a time resolution of ${\sim}30$ ps...
Nearly twenty $c\bar{c}$ pairs are produced in central Au+Au collisions at
the top RHIC energy of $\sqrt{s_{NN}}=$200 GeV, with the largest yields at
mid-rapidity. The enhanced production of charmonium states from combinations of independently produced charm quarks could contribute to the observation that, in Au+Au collisions at RHIC, J/$\psi$ yields are smaller at forward rapidity than at...
ALICE has undergone a major upgrade in preparation of LHC Run 3 (2022-2025). All detectors have been upgraded to allow readout at higher rates, matching the interaction rates provided by the LHC. The Inner Tracking System now completely consists of Monolithic Active Pixel Sensors, which also improves pointing resolution. The Time Projection Chamber has been equipped with GEM-based readout...
Strong magnetic fields are created at the early stage of non-central heavy-ion collisions. However, whether the magnetic fields survive in the late stage of heavy-ion collisions and experimental measurements of various observables are reminiscent of the initially-created magnetic fields still remain elusive. In this talk we show that fluctuations of and correlations among net baryon number,...
Due to the minimal interactions with the medium constituents, thermal dileptons emitted throughout the medium evolution are suggested as excellent probe of the hot QCD medium created in relativistic heavy-ion collisions. The invariant mass distribution of thermal dileptons can reveal the temperature of their emitting source without suffering from the blue-shift effect. By analyzing the...
ALICE pursues several upgrades to further extend the physics reach. For Run 4, ALICE is pioneering the usage of bent, wafer-scale pixel sensors to replace the three innermost layers of the inner tracking system. This makes it possible to construct truly cylindrical layers, which consist practically only of the silicon sensors. The resulting improvement in pointing resolution will allow better...
Differential studies of heavy-flavour production as a function of the event charged-particle multiplicity provide insights into the role of multi-parton interactions on heavy-quark production, the relevance of color-reconnection mechanisms in heavy-quark hadronization, and the interplay of hard and soft processes in pp, p--Pb, and Pb--Pb collisions. A complementary approach on the above...
Quarkonia and open-charm hadrons are important probes to study the properties of the Quark-Gluon Plasma (QGP). Heavy quarks are produced predominantly in hard partonic scatterings at the very early stage of heavy-ion collisions, and subsequently experience the whole evolution of the hot and dense medium. Measurements of quarkonia and open charm hadron production yields and $J/\psi$ anisotropic...
The suppression of jets in heavy-ion collisions provides a powerful method to probe the dynamics of the hot, dense plasma formed in these collisions at the LHC.
Jet quenching in heavy-ion collisions is expected to depend on the mass of the fragmenting parton as well as its QCD color charge.
For light quarks and gluons, energy loss via gluon bremsstrahlung, which is sensitive to the QCD color...
The unique forward coverage of the LHCb spectrometer allows the valence quark distributions of protons and nuclei to be probed with unprecedented precision. In this high-$x$ region, both the flavor content and structure of the nucleon's parton distribution functions remain relatively poorly known. New LHCb measurements of $Z$+charm jet production could be indicative of a valence-like...
In the scope of the FAIR Phase-0 physics program, the HADES collaboration recorded 13.7 billion Ag(1.58A GeV)+Ag events in March 2019. With an available energy of 2.55 GeV in binary nucleon nucleon collisions, the lightest hadrons containing strangeness are produced at their free nucleon nucleon threshold energy. Therefore, they are ideal probes to investigate medium effects due to their steep...
Measurements of two- and multi-particle angular correlations are presented in both $ep$ deep-inelastic scattering at $\sqrt{s}=319$ GeV and in photoproduction off protons at energies $W_{\gamma p}=270$ GeV, as a function of charged-particle multiplicity. No long-range ridge structure is observed in the correlation functions. The second-order ($V_{2∆}$) and third-order ($V_{3∆}$) azimuthal...
Electroweak W and Z bosons created in hard-scattering processes at the early stage of the collisions are efficient probes of the initial state of the collisions. While the measurements of W and Z bosons in p–Pb and Pb–Pb collisions provide insights on the nuclear modification of the parton distribution functions, the results in pp collisions are a stringent test of perturbative QCD-based...
We show that the same QCD formalism that accounts for the suppression of high-$p_T$ hadron spectra in heavy-ion collisions predicts a medium-enhanced $c\bar{c}$ pair production in high-$p_T$ jets.
Collisions of small systems at RHIC exhibit a significant suppression of the nuclear modification factor $R_{xA}$ of jets and high momentum neutral pions in events with large event activity. This suppression is accompanied by an enhancement of $R_{xA}$ in events with low event activity. Since event activity is commonly interpreted as a measure of the centrality of the collisions, these results...
The study of hypernuclei and their production mechanisms open new opportunities for nuclear/particle physics and astrophysics. The hyperons influence many nuclear properties in finite nuclei and in neutron stars (infinite nuclear matter). We review the main processes leading to the production of hypernuclei in nuclear reactions including relativistic ion collisions. Such deep-inelastic...
We found that collisional and radiative processes affect hadron and jet $R_{AA}$ with different $p_T$ dependence. It is then interesting to analyze the combined constraining power from both jet and hadron quenching to the jet transport parameter $\hat{q}$.
We conduct the study with the improved transport model (LIDO), including elastic and radiative processes, and a simple treatment of...
Z bosons and the Drell-Yan process are considered as essential probes to study the initial state effects in nuclear collisions. The CMS experiment has measured differential cross sections of Z bosons decaying to pairs of leptons in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The second order Fourier coefficient of the azimuthal distribution of Z bosons are...
To understand the in-medium effects of quarkonia in heavy ion collisions, it is necessary to perform differential studies of various observables to have a global picture of the quarkonium dynamics in the quark-gluon plasma (QGP). Recent results in proton-proton collisions have suggested that J/$\psi$ mesons are produced with much more jet activity than model predictions, which indicate that...
Space: the final frontier for antinuclei physics. There, antinucleosynthesis models already tested on the bench of hadronic colliders and particle physics experiments are put at work to crack one of the biggest problems of modern physics: the existence and nature of dark matter.
In fact, the observation of an antinucleus in cosmic rays would most probably mean a breakthrough in searches for...
One of the key challenges of hadron physics today is understanding the origin of strangeness enhancement in high-energy hadronic collisions, i.e. the increase of (multi)strange hadron yields relative to non-strange hadron yields with increasing charged-particle multiplicity. In particular, what remains unclear is the relative contribution to this phenomenon from hard and soft QCD processes and...
We compute the in-medium jet broadening $\langle p_\perp^2\rangle$ to leading order in energy in the opacity expansion. At leading order in $\alpha_s$ the elastic energy loss gives a jet broadening that grows with $\ln E$. The next-to-leading order in $\alpha_s$ result is a jet narrowing, due to destructive LPM interference effects, that grows with $\ln^2 E$. We find that in the opacity...
PHENIX has used the versatility of RHIC to map out low $p_T$ direct photon production as function of collision system size and beam energy. For systems with a size corresponding to a $dN_{ch}/d\eta$ larger than 20-30, we observe a large yield of direct photons, a large azimuthal anisoptropy with respect to the reaction plane, and a characteristic centrality dependence of $dN_\gamma/dy \propto...
Heavy ion collision experiments at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) have resulted in the creation of an exotic state of matter: the quark-gluon plasma (QGP). Over the past two decades, our understanding of the QGP has evolved significantly, from measurements of nuclear modification functions of jets due to energy loss in medium to the realization...
The ${{}^{3}_{\Lambda}\mathrm{H}}$ is a bound state of proton (p), neutron (n) and Λ. Studying its characteristics provides insights about the strong interaction between the lambda and ordinary nucleons. In particular, the ${{}^{3}_{\Lambda}\mathrm{H}}$ is an extremely loosely bound object, with a large wave-function. As a consequence, the measured (anti) ${{}^{3}_{\Lambda}\mathrm{H}}$...
Jets in relativistic heavy-ion collisions interact with the quark-gluon plasma (QGP), leading to effects such as a suppression of jet yields and modification of internal jet structure that are used to measure the properties of the QGP. This talk will show the inclusive jet nuclear modification factors in Pb--Pb collisions in various centrality classes at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV...
Understanding the initial conditions, the transport properties, and the dynamical evolution of the quark-gluon plasma are central objectives of the heavy-ion program at RHIC. The transverse momentum correlator $G_{2}\left(\Delta\eta,\Delta\varphi\right)$ has been shown to be sensitive to the shear viscosity $\eta/s$~[1,2]. On the other hand, the $\rho(v^{2}_{2},\langle p_{T} \rangle)$...
Jets are excellent probes for the study of the deconfined matter formed in heavy ion collisions. We present measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high-pT trigger hadron in pp and central Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. We compare the semi-inclusive recoil jet yields in pp and Pb-Pb collisions over a broad...
Short-lived hadronic resonances are key tools to study the hadron-gas phase that characterizes the late-stage evolution of high-energy nuclear collisions. Regeneration and rescattering processes occurring in the hadron gas can be studied by measuring the yields of hadronic resonances and comparing them with model predictions with and without the simulation of hadronic interactions....
Electromagnetic probes are one of promising tools to investigate properties of the hot and dense matter created in high-energy heavy-ion collisions. However, even the state-of-the-art phenomenological models which can correctly explain spectra and anisotropic flows of charged hadrons underpredict yield and elliptic flow of photons [1]. It is known as “photon puzzle”.
Here, we propose...
Light nuclei and hypernuclei are expected to be abundantly produced in intermediate to low energy heavy-ion collisions due to the high baryon density. However, their production mechanisms are currently not well understood. Measurements of the yield and collective flow are sensitive to their production mechanisms and the dynamics of the produced medium. In particular, hypernuclei measurements...
PHENIX has quantified the modification of jets in heavy-ion collisions due to partonic energy loss in the quark gluon plasma (QGP) by measuring the distribution of hadrons relative to a trigger particle, such as a high momentum photon or $\pi^{0}$. These two-particle correlations have revealed that high momentum hadrons are suppressed, while yield of low momentum hadrons is enhanced. This...
The formation of light (anti)nuclei in heavy-ion collisions as well as in hadron collisions has been studied experimentally and theoretically for many decades. Two competing (anti)nucleosynthesis models are typically used to describe light (anti)nuclei yields and their ratios to other hadrons in heavy-ion collisions: the statistical hadronization model (SHM) and the nucleon coalescence...
The strongly interacting matter created in high-energy heavy-ion collisions contains a multitude of conserved quantum charges, like the baryon number, strangeness, and electric charge. These conserved charges and their currents are generally coupled to each other, e.g. a baryon diffusion current also implies a current in electric charge.
In this talk, we present a novel derivation of...
In heavy-ion collisions, charm hadron production can occur via coalescence, where charm quarks combine with the surrounding light quarks in the QGP. The relative coalescence contribution is expected to be more significant for hadrons with a larger number of constituent quarks. Such an effect will contribute to the modification of the baryon-to-meson ratio in heavy-ion collisions, compared to...
The Compressed Baryonic Matter (CBM) experiment at FAIR will investigate the QCD phase diagram at high net-baryon density ($\mu_{B} > 400\ \textrm{Me}V$) in the energy range of $\sqrt{s_{NN}} = 2.9−4.9\ \textrm{Ge}V$. Precise determination of dense baryonic matter properties requires multi-differential measurements of strange hadron yields, both for most copiously produced kaons and $\Lambda$...
Analyses techniques based on multiparticle azimuthal correlations are widely used at RHIC and LHC experiments for the measurements of anisotropic flow and related phenomena. These techniques are reliable only when the number of produced particles and the values of flow harmonics are large. This limitation originates from the fact that for flow results obtained with multiparticle correlations,...
Measurements of heavy baryon production in $pp$, $pA$ and $AA$ collisions from RHIC to top LHC energies have recently attracted more and more attention, currently representing a challenge for the heavy-quark hadronization theoretical understanding.
The $\Lambda_c/D^0$ ratio observed in $AA$ collision at RHIC and LHC energies has a value of the order of the unity.
Recent experimental...
Hypernuclei are bound states of nucleons and hyperons, and thus naturally correlated hyperon-baryon systems. Hypernuclei are regarded a unique laboratory to study the hyperon-nucleon ($Y$-$N$) interaction. The $Y$-$N$ interaction is an important ingredient, not only in the equation-of-state (EoS) of astrophysical objects such as neutron stars, but also in the description of the hadronic phase...
We are proposing an experiment to study $\phi$ mass modification through $K^{+}K^{-}$ decay in p+A collisions at J-PARC. We exect to obtain several hundred thousands of $\phi \rightarrow K^{+}K^{-}$ decays in p+C and p+Cu collisions with 30 GeV proton beams. The $\phi$ mass modification is sensitive not only to the $K^{+}K^{-}$ modification but also to the branching ratio due to the small Q...
Jets including heavy flavor quarks (HF-jets) are mostly produced from initial hard scattering in relativistic heavy ion collisions. Therefore it is a good probe to study the properties of quark gluon plasma produced from heavy ion collisions. Jets initiating from bottom quarks ($b$-jets) can be identified by the characteristic of b-hadrons such as long lifetime and heavy mass. sPHENIX...
The very far forward, or ``fragmentation'', region of heavy-ion collisions is critically understudied. The physics of this region is incredibly rich and may lead to insight into a variety of other problems. We present a simple model for understanding the hydrodynamics of the fragmentation region, arguing that a density of 2-3 times nuclear saturation density is reached. We also present a...
Over the past years, considerable effort has been made to study the novel phenomena displayed by chiral systems arising from the interplay between quantum anomalies and the electromagnetic and vortical fields in a hydrodynamic framework [1]. Such novel theory is often referred to as chiral hydrodynamics. It is possible to derive the equations of motion of chiral hydrodynamics from a kinetic...
The sPHENIX detector at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) has a broad experimental QCD physics program that is highlighted by jets, their substructure, and open and closed heavy flavor production. To measure these observables, the sPHENIX tracking system is composed of a monolithic active pixel sensor based vertex detector (MVTX), a silicon strip detector...
Charm and bottom production is a powerful tool to study the properties
of the Quark Gluon Plasma (QGP).Heavy quarks lose their energies via final state interactions in the QGP.The magnitude of the energy losses is expected to depend on their mass.The elliptic flow of charm and bottom also provide a medium coupling of heavy flavor with the QGP.
PHENIX performed the statistical separation of...
In the ALICE experiment at LHC (CERN), the experimental study of quark gluon plasma with the world’s highest energy heavy ion collisions is being conducted for many years. From the LHC Run 3, a new silicon pixel detector, the Muon Forward Tracker (MFT), is installed in front of the muon spectrometer in order to improve the muon tracking in the forward rapidity region. The MFT is made of 5...
In this work, we address how the properties of a specific
hadronic probe in the form of heavy quark-antiquark bound states
can be affected in a thermal medium
of quarks and gluons with finite chemical potential ($\mu$) under
the influence of a strong magnetic field, unlike the same
in the absence of finite $\mu$ reported in the literature.
The aforesaid problem may be relevant to the...
Measurement of non-prompt $\Lambda_c^+$ production in pp collisions at $\sqrt{s}$ = 13 TeV with ALICE
Daniel Battistini for the ALICE Collaboration
In proton-proton (pp) collisions, the production of HF hadrons is typically described as a convolution of the parton distribution functions of the colliding protons, the partonic cross section, and the Fragmentation Functions (FFs). The...
The measurements of anisotropic flow in heavy-ion collisions were crucial in establishing the perfect-liquid paradigm about quark--gluon plasma (QGP) properties. Most of these results were obtained with two- and multi-particle correlation techniques, which are in an environment characterized by large multiplicities and large flow values a precision tool. However, in the flow measurements in...
The finite nuclear thickness affects the energy density $\epsilon(t)$ [1] and conserved-charge densities [2] such as the net-baryon density $n_B(t)$ produced from the primary NN collisions of heavy ion collisions. While the effects are small at high collision energies compared with the standard Bjorken model of the initial state, they are large at low collision energies, where the nuclear...
Freeze-out scenarios with separate freeze-out hypersurfaces for strange and non strange hadrons have been shown to successfully resolve the proton anomaly at the LHC and further improve the description of hadron yields across beam energy. These studies suggest that data favors an early freeze-out of strangeness. Such studies have been so far restricted within the framework of the hadron...
sPHENIX is a state-of-the-art detector for jet and heavy flavor physics in heavy-ion collisions and going to take data at RHIC in 2023. The sPHENIX MVTX detector has excellent position resolution and vertexing capabilities, which is crucial for heavy flavor physics studies. A dedicated online software system, including the quality control and detector slow control system, is being developed....
In my talk, I will present the results of a systematic investigation of the possible locations of the special point (SP), a unique feature of hybrid neutron stars manifesting in their mass-radius relation. The study demonstrates that the SP is invariant both to the choice of the low density hadronic equation of state (EoS) as well as to the two phase transition construction. This is shown in...
The creation of loosely bound objects in heavy ion collisions, e.g.~light clusters, near the phase transition temperature ($T_{\rm ch} \approx 155 MeV$) has been a puzzling observation that seems to be at odds with Big Bang nucleosynthesis suggesting that deuterons and other clusters are formed only below a temperature $T\approx 0.1-1 MeV$. We solve this puzzle by showing that the light...
The origin of possible collective phenomena in pp collisions with high final-state multiplicity still remains an open question. Recent theories explain the presence of collectivity with cold QCD effects. These can be studied in experiments by categorizing the events with transverse activity classifier $R_{\rm T}$, which is correlated to the intensity of these QCD effects. The ALICE detector...
High energy heavy-ion collisions provide an opportunity to study the production mechanism of light (anti)nuclei. There are two main possible models to explain the production mechanism - the thermal model and the coalescence model. The thermal model has been quite successful in explaining the yields of light (anti)nuclei produced in heavy-ion collisions. Thermal model suggests that the light...
In 2023, the sPHENIX experiment will begin collecting data which will include the largest recorded sample of b-hadron decays from Heavy Ion collisions at RHIC. This sample will allow for precision charm and beauty studies, part in thanks to the excellent vertexing of the MVTX detector, the timing of the INTT, and precision of the TPC along with the calorimetry system. The sPHENIX collaboration...
Heavy quarks, charm and beauty, form well before light quarks in high energy nuclear collisions. Therefore, they can probe the early, gluon rich and out-of-equilibrium stage, namely the evolving Glasma. The diffusion of heavy quarks in this system can be analyzed by coupling the Classical Yang-Mills equations for the Glasma to the relativistic kinetic equations (Wong equations) for the heavy...
Light nuclei production is a hot research topic in heavy-ion collision at RHIC-BES. The observed non-monotonic behavior with the colliding energies[1,2] was declared to be related to the critical point of the QCD phase diagram[3,4]. In this talk, we focus on investigating the light nuclei production with and without critical fluctuations within the framework of the coalescence model.
In the...
The production of heavy quarks (charm and beauty) in heavy-ion collisions occurs via hard partonic scattering processes at early times. Thus they represent a unique probe of the properties of the quark-gluon plasma (QGP), as they interact with the system throughout its entire lifetime. The heavy-flavour nuclear modification factor ($R_{\rm AA}$) and elliptic flow ($v_{\rm 2}$) are two of the...
In heavy-ion collisions, quarkonium states are used to study the properties of the quark-gluon plasma. Measurements of quarkonia in p+p collisions serve as important references. However, the production mechanism of quarkonium states in p+p collisions is still not fully understood because it involves both perturbative and non-perturbative QCD processes. Measurements of $J/\psi$ production with...
The Silicon Tracking System (STS) is planned to be the principal tracking detector of the future CBM experiment at FAIR. It will perform charged-particle track measurement with momentum resolution better than 2% in a 1 Tm dipole-magnetic field. A main challenge for the STS is to maintain high track reconstruction efficiency throughout the projected lifetime of the experiment which means being...
Soft radiative corrections to in-medium g->gg splitting processes have been known to produce double-logarithmic enhancement of the splitting rate. In our previous work on corrections to the leading order LPM effect, we have shown that this double-log enhancement is accompanied by a sub-leading single log behavior. It has been shown by previous authors that these double log enhancements can be...
The quarkonium production mechanism in elementary proton-proton (pp) collisions remains unclear. Indeed, none of the production models is able to describe it over the full kinematic range. One of the most discriminating observable between models is the polarization state of quarkonium produced in high energy collisions. The ALICE experiment has measured the polarization of inclusive J/$\Psi$...
The existence and the location of the critical end point (CEP) on the QCD phase diagram remains a puzzle. Probing the critical phenomena and locating the CEP are the key goals of the beam energy scan (BES) experiments. When approaching the CEP, the long-range correlation is established, and hence leads to a large fluctuation of the conserved charges. In this presentation, we show, based on the...
Transverse momentum broadening (TMB) of energetic partons in QCD matter plays a central role in a variety of processes studied at colliders to probe QCD ranging from jet suppression in heavy ion collisions (HIC) to TMD gluon distributions that encode information on the 3D structure of the proton and nuclei in electron-proton or proton-proton collisions. We investigate in this work [1] the...
Heavy-flavour quarks (charm and beauty) are produced on a very short time scale in initial hard-scattering processes. They experience the entire evolution of the ultrarelativistic-collision which makes them excellent probes for the characterization of the quark-gluon plasma (QGP) formed in heavy-ion collisions.
In particular, the comparison between beauty and charm measurements is a crucial...
Measurements of open-charm hadrons in ultra-relativistic heavy-ion collisions are an important part of the heavy-ion physics program of the STAR experiment. The charm quarks can be used to study the properties of the Quark-Gluon Plasma (QGP) as they are produced predominantly in hard partonic scatterings at the very early stage of heavy-ion collisions which means that they experience the whole...
Multi-particle reactions in the late stages of heavy-ion collisions are demonstrated to be significant for the final deuteron [1] and proton [2] abundances at intermediate to high beam energies. They are realized by employing a stochastic collision criterion in the hadronic transport approach SMASH.
This work sheds light on the puzzle that both final-state coalescence from nucleons and...
Top-quarks, tau leptons, and Higgs boson are the only elementary particles that have not been observed in heavy-ion collisions in the ATLAS detector yet. In particular top quarks, the heaviest elementary particles carrying colour charges, have been argued to be attractive candidates for probing the quark-gluon plasma produced in heavy-ion collisions. In proton-lead collisions, top-quark...
The Compressed Baryonic Matter (CBM) is one of the experimental pillars at the FAIR facility. CBM focuses on the search for signal of the phase transition between hadronic and quark-gluon matter, the QCD critical endpoint, new forms of strange-matter, in-medium modifications of hadrons, and the onset of chiral symmetry restoration.
The Silicon Tracking System is the central detector for...
The Compressed Baryonic Matter (CBM) experiment is a fixed-target heavy-ion physics experiment at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. The CBM physics program aims at exploring the QCD phase diagram at very high baryon densities, where a first-order phase transition from hadronic to partonic matter and a chiral phase transition is expected to occur. For...
Relativistic hydrodynamics is surprisingly predictive, even in the presence of large gradients and large deviations from equilibrium. In some of its incarnations, the method of moments can be used to justify the hydrodynamic behavior of a relativistic gas. However, it can’t be directly generalized. If long range interactions are introduced through a medium-dependent mass or a semi-classical...
Recent experimental measurements display an enhanced production of charmed baryons in high-energy nucleus-nucleus collisions. Quite surprisingly the same is found in proton-proton collisions, in which the relative yields of charmed baryons do not agree with the expectations based on e+e- collisions and with the predictions of those QCD event generators in which the hadronization stage is tuned...
The production cross sections of open heavy-flavour hadrons in pp and p-Pb collisions are typically described within the factorisation approach as the convolution of the parton distribution functions of the incoming protons, the perturbative QCD partonic cross section, and the fragmentation functions. The latter are typically parametrised from measurements in ${\rm e^+e^-}$ collisions,...
In this talk, I will describe the implementation of the kinematical constraint within the Langevin formulation of the JIMWLK equation following the proposal of Hatta and Iancu. I will discuss the numerical stability and continuum and infinite volume extrapolations. I will compare the solutions with and without the collinear improvement. I will also comment on the rapidity evolution rate of the...
The high quality experimental data on hard probes in heavy-ion collisions call for a more precise theoretical description of jet evolution in a quark-gluon plasma. To accomplish that we study jet fragmetation via $1\to 2$ final-state parton splittings in the medium. In earlier works [1,2] the authors have usually calculated these processes by invoking one or two approximations: the large-$N_c$...
Phenomenon of bending the trajectory of charged particles in a magnetic field is used as part of the particle tracking and identification system of the ALICE detector at CERN. The detector contains two electromagnets - a large solenoid which generates a magnetic field for the barrel tracking detectors of strength 0.5 Tesla, and a dipole magnet for the Muon Arm Spectrometer which generates a...
We investigate the dynamical stability of neutron stars by performing radial perturbations on their stellar structure obtained after solving the hydrostatic-equilibrium equations which uses as input a collection of equations of state obtained from successive matchings between perturbative QCD at high densities and chiral effective theory at low densities and constrained by observational data...
In this contribution, the performance of a beauty-jet tagging algorithm based on transverse impact-parameter threshold cuts will be discussed for data collected by the ALICE experiment in proton-proton collisions at $\sqrt{s}=13\,$TeV. Owing to the relatively large lifetimes and the cascade of weak decays of beauty hadrons, the measurement of the impact parameter of tracks within jets can be...
Run 3 opens the high luminosity era of the LHC. Collecting vast data samples will enable measurements with unprecedented precision. ALICE aims to record all minimum bias data at the projected 1 MHz pp and 50 kHz heavy ion collision rates. The expected data processing and storage rate will reach ~3 TB/s. To meet this challenge, ALICE underwent a major upgrade of its detectors and systems. One...
We develop a numerical method to nonperturbatively study scattering and gluon emission of a quark from a colored target using a light-front Hamiltonian approach. The target is described as a classical color field, as in the color glass condensate effective theory. The Fock space of the scattering system is restricted to the |𝑞⟩+|𝑞𝑔⟩ sectors, but the time evolution of this truncated system is...
Ultrarelativistic nuclear collisions offer an opportunity to study the production of heavy quarkonia as well as the properties of nuclear matter at extreme temperature and density. Heavy quarks are considered excellent probes to study the properties of the state of matter where quarks and gluons are deconfined, known as quark-gluon plasma (QGP) expected to be formed in nuclear...
Matter-antimatter asymmetry is a precondition necessary to explain the existence of our world made predominately of matter over antimatter. Antimatter is rare in the current universe making it difficult to study, but the Relativistic Heavy-Ion Collider (RHIC) provides us a unique opportunity to study antimatter with high-energy nuclear-nuclear collisions. In this poster, we report the...
The nature of the equation of state (EOS) of neutron stars is an open research problem. The high baryonic density and isospin asymmetry that characterize this system hinder first principle calculations of the EOS, its particle composition and in-medium particle interactions. Therefore, at the moment there is no consensus on the presence of quark matter in neutron star cores, or on the nuclear...
Multi-charm baryons containing multiple charm quarks provide a unique window on uncovering the hadronisation mechanism in the quark-gluon plasma (QGP). The production yield of multi-charm baryons from single hard scattering is negligible compared to the one by coalescence of charm quarks from multiple hard scatterings. In Pb–Pb collisions, multi-charm baryon can be formed by a combination of...
It was recently proposed that a Fixed Target (FT) program in the ALICE experiment can give access to the far backward rapidity region for p-A and Pb-A collision systems at an intermediate center of mass energy ($\sqrt{s_{\rm NN}}$ = 115 and 72 GeV for the proton and Pb beam respectively) between RHIC and SPS [1]. The structure of the nuclei can be studied at large x and as a function of the...
Currently there exists no viable ``ab initio'' approach to simulate QCD dynamics at the LHC/RHIC that is universally applicable. This profoundly limits our understanding of the formation, real-time evolution and hadronization of the quark-gluon plasma in heavy ion collisions. Quantum computing may provide a potential solution to efficiently simulate these real-time dynamics within the...
The $\Xi_c^+$ baryon is an open charm state comprised of an up, strange, and charm quark. For its peculiar composition with the presence of the strange quark, studies of baryon-to-baryon ratio of $\Xi_c^+$ to $\Lambda_c^+$ can provide valuable information on charm hadronization mechanisms, and possibly observe strangeness enhancement in small systems. We present the first study of...
Interpreting high-energy, astrophysical phenomena, such as supernova explosions or neutron-star collisions, requires a robust understanding of matter at supranuclear densities. However, our knowledge about dense matter explored in the cores of neutron stars remains limited. Fortunately, dense matter is not only probed in astrophysical observations, but also in terrestrial heavy-ion collision...
The observation of long-range azimuthal anisotropies in small collision systems triggers pressing questions concerning the applicability of fluid dynamics and whether ensembles of only a small number of particles may be effectively treated as fluids. We propose to use experiments on expanding clouds of cold atoms to answer the latter question. We consider strongly-interacting fermions confined...
ALICE 3 is a next-generation heavy-ion experiment for LHC Run 5, which will
address physics questions that are not accessible with Runs 3 and 4. One of the main goals of ALICE3 is to understand the connection between heavy quark heavy quark transport and hadronisation. One such example is the measurement of azimuthal correlations between charm and anti-charm mesons. ALICE 3 would provide...
Coalescence hadronization in QGP would enhance $\Lambda^+_c$/$D^0$ at intermediate $p_T$ and are supposed to occur in PbPb collisions.
The charmed baryon to meson ratio, $\Lambda^+_c$/$D^0$ ratio is sensitive to hadronization, can provide important information on the charm hadronization process and formation of QGP.
Prompt $\Lambda^+_c$/$D^0$ ratio are measured in peripheral PbPb collisions...
The vector $U$-bosons, or so called 'dark photons', are one of the possible candidates for the dark matter (DM) mediators. They are supposed to interact with the standard matter via a 'vector portal' due to the $U(1)-U(1)^\prime$ symmetry group mixing which might make them visible in particle and heavy-ion experiments. While there is no confirmed observation of dark photons, the detailed...
J-PARC Heavy-Ion Project (J-PARC-HI) aims at exploring high-baryon density matter in heavy-ion collisions at 1-12 AGeV/c with high-intensity frontier heavy-ion beams. We have designed a heavy-ion acceleration scheme, where a heavy-ion beam is produced in a new heavy-ion injector consisting of a heavy-ion linac and a booster ring, and further accelerated with the existing high-intensity 3-GeV...
The incoming Run 3 at LHC for ALICE will be characterized by a 50-100 times larger data-taking rate, which requires a redesign of many analysis algorithms in order to meet stricter memory and computational time constraints.
This applies especially to event mixing, which is a crucial component of correlation frameworks. Mixing is a technique of selecting distinct collisions grouped by, e.g.,...
The ALICE 3 experiment is planed as a compact, next-generation multipurpose detector at the LHC as a follow-up to the present ALICE experiment. It will provide unprecedented tracking and vertexing capabilities down to a few tens of MeV/$c$ in pp, pA and AA collisions and will have a large rapidity coverage $|\eta|<4$. Such detector performances allow to study precisely the dielectron...
Heavy quarks, namely charm and bottom quarks, serve as efficient probes to characterize the properties of the quark-gluon plasma (QGP) created in the relativistic heavy-ion collisions. The QGP evolution is modeled using relativistic viscous 3+1 D hydrodynamics approach MUSIC, initialized with a central Pb-Pb collision event using IP-GLASMA. Measured observables associated with charm quark are...
The enhanced production of strangeness was first proposed as a signature of the quark gluon plasma creation in heavy ion collisions. Recently, increased strangeness production is also observed experimentally in high multiplicity small systems such as pp and pPb collisions, where formation of QGP is not expected. In this study, production of prompt $D^+$ and $D_s^+$ in $p$Pb collisions is...
Measurements of bottomonium states in heavy-ion collisions provide a
powerful tool to study both initial-state effects on heavy-quark production
and final-state interactions between heavy quarks and the hot and dense
nuclear matter created in relativistic heavy ion collisions.
The sPHENIX experiment, which will start taking data in early 2023, plans
to measure the production of...
The composition of the fireball produced in high-energy Pb-Pb collisions at the LHC can be described by the Grand Canonical Statistical Hadronisation Model (SHM). One of the parameters of the model is the baryon chemical potential $\mu_B$, which determines the fraction of antimatter and matter present in the gas. The hypothesis that at the LHC $\mu_{B}=0$, i.e. antimatter and matter are...
The Zero Degree Calorimeter (ZDC) at the LHC is primarily a far-forward hadronic calorimeter used to measure spectator neutrons from heavy-ion collisions at the LHC. In addition to spectator neutrons, an electromagnetic module within the ZDC can be used to measure far-forward photons. The Joint ZDC Project (JZCaP) is a collaboration between ATLAS and CMS groups working on R\&D towards an...
In the core of neutron stars, extreme gravitational fields probe the stiffness of matter at very large densities. Recent neutron-star observations indicate that ultradense matter must be stiffer than previously thought, with the speed of sound potentially rising well above its asymptotic conformal limit of $1/\sqrt{3}$ [1]. Nonetheless, the implications of this large speed-of-sound peak for...
This poster presents the final recent measurements of $p_{\rm T}$-differential production cross section of charged-particle anti-$k_{\rm T}$ $R = 0.4$ b jets in pp and p--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV done by the ALICE collaboration. The production cross sections were measured down to $p_{\rm{T}}$ = 10 GeV/$c$, which is lower than in previous measurements of b jets done at...
We propose to construct a forward conversion tracker at the LHC to measure photons of a few MeV in transverse momentum, so called ultra-soft photons, which have the potential to resolve the long standing "soft-photon puzzle": Several experiments have observed an excess of ultra-soft photon production with respect to the expected yield from Low's theorem, which is very fundamentally relating...
Bottomonium states are key probes for experimental studies of the quark-gluon plasma (QGP) created in high-energy nuclear collisions. Theoretical models of bottomonium productions in high-energy nuclear collisions rely on the in-medium interactions between the bottom and antibottom quarks. The latter can be characterized by the temperature ($T$) dependent potential, with real ($V_R(T,r)$) and...
We propose a new `particlization’ prescription for the conversion of hydrodynamic degrees of freedom to hadrons at the decoupling stage of heavy-ion collisions. Unlike existing particlization schemes, this method uses only macroscopic information provided by the hydrodynamic output and follows directly from the connection between information theory and statistical mechanics. We further use...
The question of whether quark matter exists in neutron stars is a long standing one. Generally one finds that a first order phase transition from baryons to quarks softens the equation of state so much that the star would collapse into a black hole. We consider a crossover equation of state, similar to the crossover that is found in lattice QCD studies at finite temperature and zero or small...
The CBM is a next-generation experiment to be operated at FAIR facility, currently under construction in Darmstadt, Germany. Its goal is to investigate the phase diagram of strongly interacting matter in the region of high baryon-net densities and moderate temperatures, using high-intensity nucleus-nucleus collisions. The setup is designed as a forward multipurpose detector capable to measure...
Open charm hadrons are collected by the LHCb detector in proton-lead collisions at $\sqrt{s_{NN}}$=5.02 TeV. The excellent performance of particle reconstruction and identification in forward rapidity acceptance allows these charm states to be studied down to very low transverse momentum. This poster presents the LHCb measurement of the production of charm mesons, reconstructed in exclusive...
Production of light nuclei in relativistic heavy-ion collisions is well described by the thermal model, where light nuclei are in equilibrium with all other hadron species present in a fireball, and by the coalescence model, where light nuclei are formed due to final state interactions after the fireball decays. A method is proposed to falsify one of the models. We suggest to measure a...
The measurements of the spin observables open a new window for understanding the quantum properties of the hot and dense medium created in heavy-ion collisions. However, there are still several puzzling phenomena begging for satisfactory explanations. Particularly, the measured spin-alignments of the vector boson is unexpectedly large compared to a class of model calculations. To investigate...
We investigate the time evolution of strange and charm quark number densities utilizing the rate equations in the quasiparticle approach. The deconfined matter then consists of the dynamical quarks and gluons dressed by the effective temperature-dependent masses. The temperature dependence is specified by a running coupling deduced from lattice QCD thermodynamics. For the evolution of the QGP...
Strangeness production has been suggested as a sensitive probe to the early-time dynamics of the nuclear matter created in heavy-ion collisions. Transverse momentum distributions and yields of strange hadrons and resonances provide important information about the particle production mechanisms and help us to understand the properties of the created medium and its evolution in these collisions....
Two-particle azimuthal correlations triggered by electrons from heavy-flavour hadron decays can be used for heavy-flavour jet studies. By changing the momentum scales of the trigger and associated particles, the heavy-flavour jet structure can be investigated. In pp collisions, heavy-flavour correlations can be used in particular to study the production and fragmentation of heavy quarks.
In...
Quarkonium production is one of the essential probes for studying the properties of the quark-gluon plasma (QGP) created in relativistic heavy-ion collisions. The suppression of J$/\psi$ meson due to colour screening in medium and medium-induced dissociation was initially proposed as direct evidence of QGP formation. The non-prompt component of J$/\psi$ production from b-hadron decays...
We study relativistic hydrodynamics in the presence of a non vanishing spin chemical potential. Using a variety of techniques we carry out an exhaustive analysis, and identify the constitutive relations for the stress tensor and spin current in such a setup, allowing us to write the hydrodynamic equations of motion to second order in derivatives. We then solve the equations of motion in a...
Recent results of charmed baryon production in pp collisions showed significant enhancement of baryon-to-meson ratio compared with the predictions from $e^{+}e^{-}$ collisions due to the modification of the charm fragmentation fractions and possible coalescence mechanism at play. Therefore, the measurements of charmed baryon production are crucial to investigate the hadronisation mechanism of...
The sPNENIX collaboration will start data taking in 2023 at the Relativistic Heavy Ion Collider in BNL to study the Quark-Gluon Plasma and cold-QCD. A detector complex consisting of the solenoid magnet, a hadron calorimeter, an electromagnetic calorimeter, a time projection chamber, a MAPS-based vertex detector, and the intermediate silicon tracker (INTT) is under construction. A tracking...
The Silicon Tracking System (STS) is the main tracking detector of the CBM experiment. It is designed to reconstruct trajectories of charged particles with high efficiency, to achieve momentum resolution better than 2% inside a 1 Tm magnetic field, and to be capable of identifying complex decay topologies. The main STS functional building block is the detector module. It consists of a...
The Low theorem, proven only for diffractive photon radiation, cannot be extended to inelastic hadronic collisions with multi-particle production. Comparison with incorrect calculations led to the so-called soft-photon puzzle. We describe soft photon production within the color-dipole approach. The required quark distribution in the colliding hadrons at a soft scale is calculated employing the...
The Time Projection Chamber (TPC) is the main tracking and particle identification detector of the ALICE experiment at the CERN LHC. For Run 3, starting in 2022, interaction rates of 50 kHz in Pb-Pb collisions require a major upgrade of the TPC readout system. The Multi-Wire Proportional Chambers (MWPCs) were replaced by stacks of four Gas Electron Multiplier (GEM) foils, allowing continuous...
This study confronts the idea of nuclei and hypernuclei formation within the thermal model description. We have employed a newly developed chemical freezeout (CFO) parametrization method and proposed some ratios of hadrons and nuclei. By varying the decay contribution into the hadrons, we have found that these light nuclei and hyper-nuclei states are formed near the CFO boundary, even before...
Second-order theories of fluid dynamics have been successfully employed to describe the time evolution of the hot and dense matter produced in heavy-ion collisions. Nevertheless, it has been shown that the inclusion of terms that are asymptotically of third order in gradients may be required to describe the dynamics of a fluid in the extreme conditions present at the early stages of these...
The study of charm production as a function of charged-particle multiplicity allows the investigation of the role of multi-parton interactions (MPI), and provides insight into the processes occurring at the partonic level and on the interplay between the hard and soft particle production mechanisms in proton--proton (pp) collisions. In this contribution, measurements of open heavy-flavor...
The measurement of relative production rates of different charm hadrons allows us to study hadronization mechanisms of charm quarks and to investigate different hadronization models. Various hypotheses are inspected like recombination, colour reconnection and decay from unknown excited states.
The results discussed in this contribution provide the first $\Sigma_{c}^{0,++}$ production...
Stochastic processes with memory are characterized by noises that possess correlations at different times;
namely, the stochastic terms in the differential equations at a time t have memory of the noise at previous times.
Heavy ion collisions are an interesting framework in which processes with memory take place,
in particular when one considers the very early, out-of-equilibrium stage...
Light nuclei are the delicate probes of ultra-relativistic heavy ion collisions. Studying the light nuclei productions will help us to understand the nucleon emission source, the nucleosynthesis mechanism and the density fluctuations related to the critical point or first-order phase transition in heavy-ion collisions. In this talk, I will present our recent work about the beam energy...
We study the possible existence of deconfine quark matter in the core of neutron stars. A relativistic mean field model is used to describe the nuclear matter at low densities while Nambu--Jona-Lasinio model is used to describe the quark matter at high densities. A Gibbs construct is used to describe the quark-hadron phase transition at large densities and at zero temperature. Within the...
We discuss the dynamical evolution of charm quark elastic energy loss in a bulk medium at fixed temperature $T$ extending the Boltzmann (BM) collision integral to include off-shell dynamics. We show the results on the transport coefficients and the time evolution of charm quark making a comparison among the Langevin dynamics, the BM collisional integral within a Quasi-Particle Model(QPM)...
Soft theorems play a fundamental role in the development of quantum field theory. In scattering processes the production of soft photons diverges in the infrared in a controlled manner. Low's theorem relates the production cross section of a process with and without additional soft photon emission by a simple formula without dependence on the details of the process. However, this simple and...
We compute the production of J/ψ mesons in different rapidity bins as a function of event activity in p+p and p+Pb collisions at LHC energies within the color glass condensate framework combined with non-relativistic QCD (NRQCD) or an Improved Color Evaporation model (ICEM) to describe the J/ψ hadronization. We demonstrate that deviations from a linear increase of J/ψ multiplicity with...
The sPHENIX detector at RHIC is designed to perform high precision measurements of jets and heavy flavor observables to elucidate the microscopic nature of strongly interacting matter. In addition to its electromagnetic calorimeter (EMCal), the sPHENIX calorimeter system includes two hadronic calorimeters (HCals) – the inner HCal (iHCal) and outer HCal (oHCal).
The oHCal (iHCal) are composed...
Measurements of the production of heavy-flavour hadrons in proton-proton collisions
provide the baseline for the observations of hot-medium effects in heavy-ion collisions,
as well as tests of perturbative QCD calculations. Moreover, measurement of charm-
hadron production in hadronic collision systems allow investigating the charm-quark
hadronization mechanisms.
Measurements based on...
The proposed high-luminosity high-energy Electron-Ion Collider (EIC) will provide a clean environment to precisely study several fundamental questions in the high energy and nuclear physics fields. A low material budget silicon vertex/tracking detector with fine spatial resolution (hit spatial resolution < 10 $\mu$m) is critical to carry out heavy flavor hadron and jet measurements at the...
Exciting experimental results on the flow of charmonia and bottomonia with an unprecedented level of precision pose the important physics question about the possible heavy-quark thermalization in the quark-gluon plasma (QGP). In this work, a new hydrodynamic approach to the transport of heavy quarks in the QGP is presented. We exploit the conservation of the number of heavy quark-antiquark...
Understanding light (anti-)nuclei production mechanism is a long-standing challenge in heavy-ion physics. Besides its own importance, it can benefit the search of QCD critical point as well as the detection of dark matter in space. In this presentation, we present a unified description of the microscopic dynamics of light (anti-)nuclei production in high-energy nuclear collisions by solving...
Skyrme model is among the simplest extensions of chiral effective theory including anomaly. Within such framework we investigate how an external magnetic field deforms a Skyrmion while preserving its topological winding. A crystal constituted by multiple magnetically deformed Skyrmions provides us insights of the ground state of nuclear matter in strong magnetic field. We manifest such Skyrme...
The free energy density of N=4 supersymmetric Yang-Mills theory in four space-time dimensions is derived through second order in the 't Hooft coupling λ at finite temperature using effective-field theory methods. The contributions to the free energy density at this order come from the hard scale T and the soft scale λ√T. The effects of the scale T are encoded in the coefficients of an...
The PHENIX experiment at RHIC has a special ability to detect muons at the region $1.2<|y|<2.2$ from heavy quarks which are studied extensively to understand their production and modification in high energy hadron-hadron collisions. Quarkonia states like $J/\psi$ and $\psi(2S)$ of different binding energies are expected to have their yields modified differently by the medium or comoving...
The formulation of a causal and stable theory of relativistic viscous hydrodynamics is an important field of current research, with direct applications to the modeling of ultrarelativistic heavy-ion collisions. While the theory of relativistic ideal fluids is well established, the incorporation of dissipation introduces qualitatively new challenges due to the need to maintain relativistic...
Model emulation is an important tool for tackling many nuclear physics problems, including an estimation of model parameters. As Bayesian parameter estimation becomes more common in heavy-ion physics, there is a need for an analysis package to facilitate such projects and to reduce efforts duplication. While the Bayesian statistical formalism handles this exists, the Bayesian Analysis of...
Suppression of open heavy flavors and quarkonia in heavy-ion collisions is among the most informative probes of the quark-gluon plasma. Interpreting the full wealth of data obtained from the collision events requires a precise understanding of the evolution of heavy quarks and quarkonia as they propagate through the nearly thermal and strongly coupled plasma. In particular, a complete...
A novel hybrid approach coupling the hadronic transport approach SMASH to the 3+1D viscous hydrodynamics code vHLLE is introduced. The SMASH-vHLLE-hybrid is suitable to describe heavy-ion collisions ranging from $\sqrt{s}_\mathrm{NN}$ = 4.3 GeV - 5.02 TeV and is publicly available on Github. This talk focuses on collisions towards the high baryon-density regime of the QCD phase diagram, where...
The measurement of heavy-flavour (charm and beauty) production in proton-proton (pp) collisions at the LHC provides a crucial information about quantum chromodynamics (QCD) in high-energy regime. Due to their large masses, heavy quarks are mainly produced in initial hard scattering processes. Therefore, heavy-flavour production cross section represents a primary benchmark for perturbative QCD...
Heavy-quark production in nuclear collisions is an important tool to access the properties and evolution of deconfined matter. Corresponding studies on pp collisions serve as a reference process, as well as a test of various aspects of QCD. A detection technique that was little explored until now at LHC energy is the analysis of the high-mass region of the dilepton invariant mass spectrum...
The CBM experiment at FAIR aims to explore the QCD phase diagram at high net baryon density and moderate temperature by colliding heavy nuclei in the energy range 4-12 AGeV. The Muon Chamber (MuCh) detector at CBM is dedicatedly designed to detect muon pairs originating at different phases in the evolution of the fireball produced in nuclear collisions. MuCh consists...
The deconfined quark-gluon plasma (QGP) created in relativistic heavy-ion collisions is not only a perfect fluid with very small $\eta/s$ but also a most "charming" system with hundreds of charm quarks. Meanwhile, it is widely accepted that the quark hadronization mechanism changes with the appearance of QGP. The production of charmed hadrons differs significantly in $A$-$A$ collisions from...
The Compressed Baryonic Matter experiment (CBM) at FAIR is designed to measure nucleus-nucleus collisions at an unprecedented interaction rate of up to 10MHz which will allow the study of extremely rare probes with high precision. To achieve this high rate capability, CBM will be equipped with fast and radiation-hard detectors, which are readout via a triggerless-streaming data acquisition...
The sPHENIX experiment is currently under construction and will be commissioned for data taking in 2023 at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The sPHENIX Event Plane Detector (sEPD) will be a new detector sub-system that can be installed into sPHENIX and deliver measurements of jet quenching anisotropy. The sEPD comprises two scintillator disks, one...
The magnetic field seems to play a significant role in shaping and working the visible universe. It gives rise to a lot of non-trivial and anomalous behavior in the system in which they are present, extending from the effects seen in condensed matter physics in Dirac and Weyl semi-metals to large cosmological objects like in neutron stars or black holes. The strength of the magnetic field in...
The charm quark at energies of the LHC and above is expected to remain well out of chemical equilibrium,with its abundance dominated by initial stage production, and yet be abundantly enough produced ($N_{c\bar{c}} \simeq 10^2$) for coalescence to be non-negligible.
Using a simple analytically solvable model, we argue that it makes charmonium abundance the ideal probe of remnants of...
Determining the existence and the location of the QCD critical point remains a major open problem, both theoretically and experimentally. In this work, I present a new way of reconstructing the equation of state in the vicinity of the nearest thermodynamic singularity (the Lee-Yang edge singularity in the crossover region) from a truncated Taylor series expansion in baryon chemical potential....
The upcoming high-luminosity measurements at RHIC and LHC will generate heavy flavor data with unprecedented precision. How to utilize the high-$p_\perp$ heavy flavor data to analyze the interaction mechanisms in the quark-gluon plasma? For this, we employ our recently developed DREENA framework based on our dynamical energy loss formalism. We will propose: i) How to disentangle the relevance...
We present a new measurement studying the relationship between the production of hard and soft particles through the correlation of Upsilon meson states with the inclusive-charged particle yields in 13 TeV $pp$ collisions. Measurements are made differentially for Upsilon momentum and for different Upsilon states. The analysis is performed using the full-luminosity ATLAS Run-2 13 TeV $pp$ data....
In the original DNMR derivation [1], irreducible moments are used to derive the evolution equations of second order hydrodynamics for the dissipative quantities (bulk viscous pressure, diffusion current and shear tensor) from kinetic theory. In general, this procedure gives rise to terms of order Kn^2 (second order in gradients), which are parabolic in nature and thus acausal. In this...
In preparation for the LHC Run 3, which will provide collisions at higher luminosity and center-of-mass energy, the ALICE experiment has introduced new detectors in addition to upgrading the existing detectors. As a part of this upgrade, a new silicon pixel tracking detector named Muon Forward Tracker (MFT) with an excellent positional resolution is installed in the forward rapidity region. By...
Transverse mass scaling has been observed for a wide range of particle
species in $pp$ collisions at various energies from the SPS to RHIC and
the LHC. The observed scaling is different for baryons and mesons, and
in this work, we present a comprehensive study of the $m_{T}$-scaling at
LHC energies also extended to the heavier mesons. The study reveals a
systematic pattern in the scaling...
The NA61/SHINE experiment at the CERN SPS obtained new data on proton and pion collective flow in Pb+Pb collisions, and on the distortion of charged pion spectra by the spectator electromagnetic field in Ar+Sc reactions. The latter is the first ever measurement of this effect in small systems at the CERN SPS.
The data on both effects are shown as a function of collision centrality and...
