Two-particle correlations are presented for $\mathrm{K^{0}_S}$, $\Lambda$, and $\bar{\Lambda}$ strange hadrons as a function of relative momentum in lead-lead (PbPb) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV with data samples collected by the CMS experiment. These correlations are sensitive to quantum statistics and to final-state interactions between particles. The...
Recent measurements of the production of charm hadrons at midrapidity in pp collisions at $\sqrt s$ = 5.02 and 13 TeV showed that the baryon-to-meson yield ratios are significantly larger than those measured in $\rm e^{+}e^{-}$ collisions for different charm-baryon species. These observations suggest that the charm fragmentation fractions are not universal and that the baryon-to-meson ratios...
Two-particle correlations are used to extract the space-time and dynamical information of the particle-emitting source created in heavy-ion collisions. The source radii extracted from these correlations characterize the system at the kinetic freeze-out, i.e., the last stage of particle interactions. Kaons can provide a more direct view of the particle-emitting source than pions as they have...
The Electron-Ion Collider (EIC) at Brookhaven National Laboratory will be an experimental facility to explore gluons in nucleons and nuclei, shedding light on their structure and the interactions within. The ePIC detector will be the first experiment at the EIC dedicated to detailed studies of nuclear structure in electron-proton and electron-ion collisions.
The ambitious physics program of...
In this contribution, we extend the scope of the JETSCAPE framework to cover the jet radius ($R$) dependence of the jet nuclear modification factor, ${R_{AA}}$, for broader area jet cones, going all the way up to $R$ = 1.0. The primary focus of this work has been the in-depth analysis of the high-${p_{T}}$ inclusive jets and the quenching effects observed in the quark-gluon plasma formed in...
Electromagnetic radiation is emitted throughout the whole evolution of high-energy heavy-ion collisions. Due to their penetrating nature, real and virtual photons reach the detector unimpeded. Their measurement makes it possible to shed light on the different stages of the extreme states of matter created in such collisions.
In this poster, we will discuss dielectron measurements that will...
We demonstrate that the early stages of the bottom-up thermalization scenario [1] are well described by the adiabatic hydrodynamization framework, thus providing novel analytic results on the thermalization process of QCD in a heavy ion collision. These results provide an intuitive explanation of why a gas of quarks and gluons can relax so quickly towards equilibrium, and provide a starting...
The production of deuterons in pp collisions at $\sqrt{s}=$ 13 TeV is simulated on an event-by-event basis using a coalescence afterburner based on a state-of-the-art Wigner-function formalism, and EPOS 3 and PYTHIA 8.3 as event generators. The space-momentum correlations of the nucleon pairs provided by the event generators are preserved, while the nucleon-emitting source is modelled such to...
Hypernuclei are bound states of nucleons and hyperons. The study of their properties, such as their lifetimes and binding energies, provide information on the hadronic interaction between hyperons and nucleons which are complementary to those obtained from correlation measurements. Precise modeling of this interaction is a fundamental input for the calculation of the equation of state of...
The spin alignment of vector mesons emitted in heavy-ion collisions has recently been measured by the ALICE and STAR collaborations over a wide range of energies [1, 2]. The alignment is part of the so-called tensor polarization, which is a property that is exclusive to particles of spin 1 and higher. Even though there have been substantial theoretical efforts, a definite explanation for the...
The quark-hadron transition that happens in ultra-relativistic heavy-ion collisions is expected to be influenced by the effects of rotation and magnetic field, both present due to the geometry of a generic non-head-on impact. We augment the conventional $ T$--$\mu_B$ planar phase diagram for QCD matter by extending it to a multi-dimensional domain spanned by temperature $T$, baryon chemical...
We present an innovative procedure to account for unavoidable contributions from volume (or system size) fluctuations to experimentally measured cumulants of particle multiplicity distributions produced in relativistic nuclear collisions. For the first time we extract participant fluctuations directly from the data used for the fluctuation analysis, i.e., without involving model calculations...
Isobar collisions, $^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr, at $\sqrt{s_{\mathrm {NN}}}$ = 200 GeV have been performed at RHIC. These collisions are considered to be an effective way to minimize the flow-driven background contribution to search for the possibly small CME signal. Anisotropic flow is an important tool to understand properties of the QGP medium. Elliptic...
Multiple evidence reveals that the vast majority of the matter content of the universe is non baryonic and electrically neutral. This component is usually called Dark Matter (DM), for its lack of electromagnetic interactions, and is measured to constitute about 25% of the energy density of the Universe. The most common hypothesis is that it consists of weakly interacting massive particles,...
The long-range ($|\Delta\eta| \gt 2$) near-side ($\Delta\phi\approx0$) ridge structure in a two-particle correlation analysis has been observed in heavy ion collision, which was well-explained by the hydrodynamic models based on the quark-gluon plasma (QGP) effect. However, even though small systems such as pp and pPb collisions cannot have enough density and temperature to create the QGP...
Heavy-flavor (charm and beauty) quarks are generated primarily via hard scattering processes in high-energy hadronic collisions, and then undergo parton shower (fragmentation) and hadronization. Two-particle azimuthal correlations of heavy-flavor particles is a differential measurement which allows for the study of the fragmentation of heavy quarks. By measuring the azimuthal correlation in...
The beauty quark is a unique probe to study the properties of quark-gluon plasma thanks to its large mass and relatively long thermal relaxation time compared with lighter partons. Traditional experimental observables such as elliptic flow v$_2$ and nuclear modification factor R$_{AA}$ of fully reconstructed beauty hadrons have been measured at the LHC. Moreover, indirect measurements on...
Beauty quarks are produced in hard-parton scatterings in the early stages of the partonic collisions. They are the ideal probe to investigate the properties of Quark-Gluon Plasma (QGP) produced in ultra-relativistic heavy-ion collisions as they experience the whole QGP evolution. Due to their large mass, their production can be calculated using perturbative Quantum Chromodynamics (pQCD), thus...
In ultra-relativistic heavy-ion collisions, the colliding nuclei are decelerated and kinetic energy is converted into new particles. This energy loss is referred to as baryon stopping. A fundamental question one can ask in the study of high energy heavy-ion collisions is how much baryon stopping there is. This can be quantified by measuring the net proton rapidity distributions. Previous...
Fluctuations of conserved quantities are proposed as a powerful observable to search for the QCD critical point. Recently, proton cumulants from central Au+Au $\sqrt{s_{NN}}$ = 3 GeV collisions were reported, which implies that hadronic interactions are dominant at 3 GeV and the QCD critical point could exist at the collision energies higher than 3 GeV. The baryon-strangeness correlation is...
The sPHENIX TPC readout will use an array of quadruple-stacked gas electron multiplier (GEM) modules to amplify signals from the chamber in order to perform precise tracking measurements. The performance of the system may be affected by a shift in the readout baseline due to event-by-event fluctuations. These fluctuations are a result of the common-mode noise generated in the induction gap of...
Ultra-relativistic heavy-ion collisions at RHIC are thought to have created a Quark-Gluon-Plasma (QGP) with a very low shear viscosity in the deconfined phase. However, as the QGP hadronizes it will evolve through a hadronic phase with rapidly increasing shear viscosity. In order to fully characterize the QGP state, one has to separately determine the viscosity of the hadronic phase. Although...
High-energy heavy-ion collisions offer a unique and precise way to probe nuclear structures by providing a snapshot of the nuclear distribution at the time of the collision, which is complementary to low-energy nuclear physics experiments.
In this talk, we present a comprehensive scan of flow observables, including anisotropic flow coefficients, nonlinear flow modes, and normalized...
The sPHENIX Time Projection Chamber (TPC) is a gaseous drift detector
designed to measure charged particle tracks. It is filled with Argon/CF4 and uses
Gaseous Electron Multiplier (GEM) foils at readout for electron amplification
and ion back-flow suppression. The electrons at readout are measured, converted
to digital current, and their signal waveforms are processed to reconstruct the...
The Time Projection Chamber (TPC) is the main tracking detector in sPHENIX. Charged particles which pass through the TPC ionize the gas, with the transverse position being given by the readout pad and the time for the ionization electrons to drift to the endcaps defining the z position. The ionization electrons are clustered together in order to track particles and determine their momenta. In...
The sPHENIX Time Projection Chamber (TPC) serves as the main tracking detector of the sPHENIX experiment, which began operating at the Relativistic Heavy Ion Collider at Brookhaven National Lab this year. It operates with a quadruple-GEM avalanche stage which provides gain while restricting the flow of ions back into the chamber sufficiently to operate in streaming mode, without any...
The multiplicity distribution measures the probability of obtaining a certain number of particles in a given collision and is one of the first observables measured in data at each new collision type and center of mass energy. It is relevant since is one of the fundamental observables to describe the global properties of the interactions and is sensitive to non-linear QCD evolution in the...
Multiplicity distributions of primary charged particles are sensitive to non-linear QCD evolution in the initial state. We present the distributions in various pseudorapidity ranges in proton-proton collisions at $\sqrt{s}$ = 13.6 TeV. Charged particles are reconstructed using the Inner Tracking System that has been upgraded for Run3 at LHC and is operation starting in 2022. The data are...
sPHENIX, the first detector to be built at the Relativistic Heavy-Ion Collider (RHIC) in over two decades, will bring unprecedented measurement capabilities at RHIC energies. One of the initial physics measurements to be performed by sPHENIX concerns the charged-particle multiplicity, which utilizes the tracklet analysis method with the cluster information from the...
We study the production of charm quarks in hot QCD medium described by quasiparticle excitations of quarks and gluons. The effective masses are adjusted through the coupling to satisfy the entropy density obtained on the lattice [1]. The evolution of the QGP is described by hydrodynamic simulations in (2+1) dimensions with temperature-dependent shear viscosity taken into account [1,2]. The...
Quarkonium production is considered one of the golden probes of the quark-gluon plasma (QGP) formation in heavy-ion collisions.
Due to their large mass, the production of heavy-quarks is governed by hard scales of QCD, while the formation of the bound quarkonium state involves soft QCD scales.
The regeneration process of J/$\psi$ in the QGP or at the phase boundary is crucial for describing...
The AdS/CFT correspondence, which connects strongly coupled conformal field theories in $N$ dimensions to gravity in $N+1$ dimensional Anti-de Sitter space, has provided valuable insights into the non-perturbative aspects of QCD. Soft-wall AdS/QCD is a phenomenological model that uses a dilaton field to introduce confinement, while a scalar field is dual to the chiral condensate. The...
Balance functions have been extensively used to elucidate the time evolution of quark production in heavy-ion collisions. Early models predicted two stages in the quark production, one for light quarks and one for the slightly heavier strange quark, separated by a period of isentropic expansion. This led to the notion of clocking the particle production and tracking radial flow effects. The...
Many physics observables of interest in heavy-ion collisions require knowledge of the collision geometry. Geometric fluctuations lead to different symmetry planes of the initial geometry for each harmonic number, called participant planes. As the produced medium evolves, pressure gradients transform the initial state spatial anisotropy into final state momentum anisotropy. The angular...
We present a relativistic density functional approach to color superconducting quark matter that mimics quark confinement by a fast growth of the quasiparticle self-energy in the confining region [1]. The approach is shown to be equivalent to a chiral model of quark matter with medium dependent couplings. The approach to the conformal limit at asymptotically high densities is provided by a...
The new sPHENIX detector at RHIC will begin commissioning with Au+Au collisions at 200 GeV in Spring 2023, followed by p+p and p+Au data taking in 2024. The experiment combines triggered readout of the calorimeter system with streaming readout of the tracking detectors in a hybrid readout scheme. The hybrid readout scheme enables a large increase in the collected statistics in particular for...
Net-charge, net-strangeness and net-baryon number fluctuations measured in ultra-relativistic heavy-ion collisions may reveal details and insights into the quark-hadron transition, hadro-chemical freeze-out and possibly aid in the search of the QCD critical point. By controlling the collision energy, some current and upcoming heavy-ion facilities aim to study high energy nucleus-nucleus...
Constructed at Lehigh University between 2021 and 2023, the sPHENIX Event Plane Detector (sEPD) will measure charged particle multiplicity at forward rapidity from the collision of hadrons. This detector consists of 24 triangular sectors, each of which is divided into 31 optically isolated tiles of plastic scintillating material, such that light can be collected from a discrete area of the...
HADES has a large acceptance as well as excellent particle identification capabilities and therefore allows the study of dielectron, hadron, and light nuclei production in heavy-ion collisions with great precision. The harmonic flow coefficients $v_n$ of the order $n = 1 − 6$ are measured with HADES as a function of centrality, transverse momentum, and rapidity in Au+Au collisions at 1.23...
Correlations involving the seven conserved quantities, $\{E,\vec{p},Q,S,B\}$, were modeled for heay-ion collisions at finite baryon density. The evolution of correlations as a function of relative rapidity was treated as a linear response to local thermodynamic fluctuations of on the Bjorken-model background. The entire 7x7 matrix of correlations was found to be significant, sensetive to the...
Correlations between net-conserved quantities such as net-baryon, net-charge and net-strangeness are essential probes of QCD phase structure and are related to the ratios of thermodynamic susceptibilities in lattice QCD calculations. The study of these correlations can probe thermal conditions in a medium and help to elucidate the nature of the strongly interacting matter formed in high-energy...
We present energy loss predictions of B and D-mesons at $\sqrt{s}=200$ GeV in pA collision systems. We assume that the medium produced in these collisions is strongly coupled, and show the centrality and momentum dependence of the nuclear modification factor at midrapidity. We also quantify the systematic theoretical uncertainties in these predictions that are a result of the mapping of...
Studies of charm production in proton-proton ($pp$) collisions are essential to understand some of the most fundamental aspects of Quantum Chromodynamics. They also provide the baseline for interpretation of charm data from larger colliding systems. Over the last decade, the measurement of the production cross-sections of charm mesons and baryons in $pp$ collisions has been at the centre of a...
In this poster, PHENIX presents a proof of principle study for the measurement of prompt and non-prompt $e^{+}e^{-}$ pair production in the intermediate mass range ($m_{\phi}$ $<$ $m_{ee}$ $<$ $m_{J/\psi}$) using $p$+$p$ data at 200 GeV taken in 2015. PHENIX plans to extend the measurement to the high statistics Au+Au data-set recorded in 2014 and 2016, with the goal to isolate the expected...
Results from heavy-ion collisions confirmed the scenario in which the deconfined state of nuclear matter, dubbed the quark--gluon plasma (QGP), undergoes a collective expansion. Collective anisotropic flow, quantified with Fourier harmonics of azimuthal distribution of particles, $v_n$, is one of the most sensitive experimental probes to constrain QGP properties. Recently developed...
In this contribution we present results on the dielectron production in $Ag+Ag$ collisions (0-40% centrality) and $p+p$ interactions at $1.58 \, AGeV$ beam energy measured with the High Acceptance DiElectron Spectrometer (HADES). The HADES RICH detector has been upgraded with a new photon detection camera which strongly enhances the electron efficiency and...
The anisotropic flow parameters $(v_{n})$ offer insights into collective hydrodynamic expansion and transport properties of the produced medium at higher collision energies, while they are sensitive to the compressibility of the nuclear matter and nuclear equation of state at lower collision energies. Among them directed flow ($v_1$) describes the collective sideward motion of produced...
Studying hyper-nuclei production and their collectivity can shed light on their production mechanism as well as the hyperon-nucleon interactions under finite pressure. This is a unique opportunity for heavy-ion collisions at high baryon density region where hypernuclei production rate increases.
In this poster, we will present $v_{1}$ of the hyper-nuclei ($\Lambda$, $^{3}_{\Lambda}{\rm...
Directed flow of particles is an important feature seen in heavy-ion collisions and is a sensitive probe to the equation of state (EoS) of the matter produced in the collisions. Model calculations have also predicted that directed flow could be sensitive to the softening of EoS associated with a first order phase transition. Directed flow of protons and anti-protons are also of interest as...
The Time Projection Chamber (TPC) to be used for tracking and particle identification in the sPHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) is expected to experience significant distortions from build-up of backflowing ions created by the combination of high collision rates and amplification from Gas Electron Multiplier (GEM). By integrating the digitized readout from the...
The nuclear modification factor related to the Drell-Yan (DY) production cross-section is an excellent probe of the cold nuclear matter (CNM) properties. The acceptance of the sPHENIX detector allows detection of DY events in the dielectron channel for p$_\perp$ ≳ M, where p$_\perp$ is the dilepton transverse momentum and M its invariant mass. In this kinematic region, the DY cross-section is...
In the chiral limit the complicated many-body dynamics around the second-order chiral phase transition of two-flavour QCD can be understood by appealing to universality. We present a novel formulation of real-time functional renormalization group that describes the stochastic hydrodynamic equations of motion for systems in the same dynamic universality class, which correspond to Model G in the...
We analyze the effect of hydrodynamic fluctuations on normalized mixed harmonic cumulants ($nMHC$) [1,2] for the first time based on event-by-event simulations of high-energy heavy-ion collisions using an integrated model of an initial state model, stochastic causal fluctuating hydrodynamics, and a hadronic afterburner.
For the quantitative constraints on the transport properties of...
In heavy ion collisions, the initial state geometry plays a crucial role in determining final state observables such as elliptic flow $v_2$ and radial flow reflected by event-wise average transverse momentum $[p_{\rm T}]$. The initial state geometry is influenced by several nuclear shape parameters, including quadrupole deformation (β), triaxiality (γ) [1], nuclear radius (r), and skin depth...
Jets are excellent probes for studying the deconfined matter formed in heavy ion collisions. However, competing energy-loss effects, such as the dependence on the opening angle of the shower, radiative emissions to large angles, and the medium response to the jet, can obscure interpretation. This talk presents two new observables aimed at disentangling these effects. First, we introduce a new...
Chiral media, such as quark-gluon plasma, possess a number of unique properties originating from the quantum phenomenon of the chiral anomaly. These properties can be measured by observing the propagation of fast charged particles moving through the medium and the radiation produced in the process. We show how the chiral anomaly confers distinctive features onto the particle energy loss and...
Energy-energy correlators (EEC) offer a novel way to study the structure of jets. Defined as the energy-weighted cross section of particle pairs inside jets, the correlation strength as a function of the pair opening angle allows a distinct separation of the perturbative and non-perturbative regimes. The evolution of parton dynamics in jets to their confinement into hadrons can be studied....
Energy-energy correlators (EEC) have been proposed to study the structure of energy flow within jets. These functions are defined as the energy-weighted cross-section of particle pairs inside jets. The correlation as a function of pair distance and jet transverse momentum offers a clear separation between the perturbative and non-perturbative regimes, where one can probe the dynamics of quarks...
In an effort to better understand the thermal-like behavior and particle yields seen in p-p collisions we recast the problem employing the principles of quantum states and their entanglement in the produced system. We seek to show that this entanglement in the initial state has a measurable effect on the evolution of the system and is the driving mechanism behind the thermal-like behavior and...
Multiplicity data on $\rm\bar{p}$p/pp collisions at {\footnotesize SPS} and {\footnotesize LHC} energies (0.2-7 TeV) are used to study the entropy production, dimensions and other multifractal characteristics of multiplicity distributions of relativistic charged particles produced. It is observed that the entropy produced in smaller and(or) larger phase space bins, when normalized to maximum...
Measurements of azimuthal correlations of charmed mesons in high-energy heavy-ion collisions can shed light on the transport properties of the Qaurk-Gluon Plasma. The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) collected in 2014 and 2016 a large sample of Au+Au reactions at $\sqrt{s_{NN}}$ = 200 GeV making such a study possible. The sPHENIX experiment will also offer a...
A hot and dense system formed in heavy-ion collisions can be characterized by studying the scaling behavior of the spatial distributions of the produced particles. In this contribution, we present intermittency analysis of the normalized factorial moments ($F\rm{_{q}}$) of the multiplicity distributions of the charged particles produced in Pb--Pb collisions as a function of phase-space...
Hadronic resonances are interesting candidates to study the properties of the hadronic phase, which is the time span between the chemical and kinetic freeze-outs, formed during the evolution of relativistic heavy-ion collisions. Due to their short lifetimes, comparable to the lifetime of hadronic phase ($\sim$10 $-$ 12 fm/$c$), they decay in the hadronic phase and their decay products undergo...
The investigation of light hadrons in UPCs is of great interest for QCD studies. ALICE is a superb detector for studying these processes because of its excellent particle identification and tracking capabilities. The measured cross section of coherent $\rho^{0}$ mesons in photon-lead interactions has been found to be about 40% smaller than what is predicted by the Glauber model, and...
The Chiral Mean Field model (CMF) has been successful in describing the equation of state at large baryon densities, such as those found in neutron stars, neutron star mergers, and heavy-ion collisions. The MUSES collaboration has rewritten the zero-temperature CMF model from Fortran 77 into a parallelized modern C++20 using OpenMP, which has resulted in at least an order of magnitude...
Heavy-ion collisions produce a quark-gluon plasma that undergoes rapid expansion and cooling, which presents a challenge for calculating jet quenching observables. Current approaches rely on analytical results for static cases, introducing theoretical uncertainties and biases in our understanding of the pre-equilibrated medium. To address this issue, we employ analytical re-summation schemes...
The thermal fluctuations in the QGP medium formed in heavy ion collisions present themselves as event-wise $[p_\mathrm{T}]$ fluctuations in the final state. Recent studies have shown that the average and higher-order fluctuations of $[p_\mathrm{T}]$ in ultra-central collisions are sensitive to radial flow, random thermal motion, and nuclear deformation, and can provide constraints on the...
Recent measurements in proton-proton (pp) and proton-lead (p--Pb) collisions have shown features that are reminiscent of those observed in lead-lead (Pb--Pb) collisions, such as near-side long-range correlations, mass-dependent hardening of ${p}_{\mathrm T}$ spectra, strangeness enhancement etc. Therefore, one of the key challenges today is understanding the origin of strangeness enhancement...
We investigate the characteristics of gluonic cascades in static and expanding media by numerically solving the complete BDIM (Blaizot-Dominguez-Iancu-Mehtar-Tani) evolution equations in longitudinal and transverse momentum using the Monte Carlo event generator MINCAS. In this analysis, we compare angular distributions of in-cone radiation across various medium profiles with effective scaling...
It is well established that the late states of a high energy nuclear collision can be described in terms of relativistic fluid dynamics. An open problem in this context is how the actual collision and the early time dynamics directly after it can be described. Phenomenological models are currently employed here and they have several parameters that need to be fitted to experimental...
The origin of hadron masses cannot be attributed to the Higgs mechanism alone. On top of that, the spontaneous breaking of chiral symmetry potentially restored at extremely high temperatures, plays an important role. Low-mass vector mesons (ρ, ω, φ) are highly sensitive to chiral symmetry restoration effects, and their electromagnetic spectral function is expected to be modified in Pb-Pb...
Exploring the space-time extent of particle production is 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, femtoscopic (momentum) correlations are utilized to gain information about the space-time geometry of the particle emitting source....
NA61/SHINE has measured the first deuteron production in proton-proton interactions at 158 GeV/c (sqrt(s) = 17.3 GeV). These measurements will be presented and compared to different nuclear formation models. The two most prevalent formation models—the thermal and coalescence models—are based on different underlying physics. A better understanding of (anti)nuclei production mechanisms is...
Besides the traditional flow studies of individual flow amplitudes $v_n$, independent information about all stages in heavy-ion evolution can be extracted from multi-harmonic correlations of flow amplitudes. The simplest realization is Symmetric Cumulants (SC), which correlate the same-order moments of two or more flow amplitudes. In recent studies, it was demonstrated that SC can reveal the...
Accurate knowledge of the strong interaction between charged kaons and (anti)deuteron is a missing piece of information in the field of the low-energy (anti)kaon-nucleon interactions for more than 40 years. The interaction between charged kaons and (anti)deuterons is a complex subject at both experimental and theoretical levels. From the experimental point of view, so far scattering cross...
The first results on identified hadron spectra produced in central Xe+La collisions at SPS will be presented. The kinematic distributions and measured multiplicities of identified hadrons will be compared with previously released by NA61/SHINE results on p+p, Be+Be, Ar+Sc and NA49 Pb+Pb results, as well as with available world data.
Obtained results, and in particular ratio of positively...
Higher order flow harmonics provide a powerful probe of the initial geometry of heavy ion collisions, as well as the properties of the quark-gluon plasma produced in these collisions, including the transport coefficients and the degree of collective behavior. This poster presents higher order flow harmonics measurements in PbPb collisions at $\sqrt{s_{_{\mathrm{NN}}}} = 5.02$~TeV using data...
Forward and backward rapidity regions are rich laboratories to explore several effects which happens to a probe before and after its hard scattering. The large rapidity region may also experiment a different dynamics for strangeness enhancement seen in heavy ion collisions at RHIC and LHC. The PHENIX experiment has a long history of large rapidity measurements with the muon spectrometers...
Various interesting phenomena have been predicted to occur in a quark-gluon plasma produced in relativistic heavy-ion collisions due to a strong magnetic field which is also generated in these collisions. However, none of these predictions has been convincingly confirmed experimentally yet. So, the question is why? Our aim is to systematically discuss the problem of magnetic field generation....
The sPHENIX experiment at RHIC will begin commissioning with Au+Au data in Spring 2023. The Monolithic Active Pixel Sensor (MAPS) based Vertex Detector (MVTX), the Intermediate Silicon Tracker (INTT) and the Time Projection Chamber (TPC) at sPHENIX can provide high precision primary/displaced vertex and track reconstruction in the pseudorapidity region of $|\eta| \le 1.1$. The sPHENIX...
Heavy quarks serve as effective probes of relativistic heavy-ion collisions as they are created in the initial stages of the collision event and exist at all stages. We study the dynamics of heavy flavors using a hybrid framework that incorporates the MARTINI event generator, pythia8.1 for the initial production of heavy quarks, and Langevin dynamics to describe the evolution of heavy quarks...
The sPHENIX experiment will begin commissioning in Spring 2023 at the Relativistic Heavy Ion Collider (RHIC) at BNL, presenting a unique opportunity to study QGP properties using jets and heavy quarks with unprecedented precision. The successful construction and deployment of the three-layer Monolithic-Active-Pixel-Sensor (MAPS) based VerTeX detector (MVTX) for the sPHENIX experiment in 2023...
The early stage of high-energy nuclear collisions is dominated by strong gluon fields called the evolving Glasma. This stage can be probed by heavy quarks (HQs), charm and beauty, since they are produced almost immediately by hard scatterings. We study the propagation of HQs in the evolving Glasma fields, by solving the relativistic kinetic equations that couple the HQs to the fields...
Owing to its spectrometer acceptance, which is complementary to the other
LHC experiments, LHCb is collecting several fixed-target and ion collision sam-
ples, providing unique inputs to theoretical models in poorly explored kinematic
regions. In this contribution, the impact of the ongoing and foreseen upgrades
of the LHCb experiment on the ions and fixed-target physics programme...
Relativistic hydrodynamics has been successful in describing space-time evolution of matter created in high-energy nuclear collisions. It is conventionally supposed that the created matter starts to behave as fluids all at once at a certain initial time. It is, however, not at all trivial from which stage after the collision the fluid picture can be applied to the system. According to the...
Reconstructing hyperons with high purity and high reconstruction efficiency is essential for measurements of hyperon-hyperon correlation and searches for exotic strange hadrons, which are both presently discussed topics in the QCD community. Hyperons can be abundantly produced in Pb-Pb collisions at LHC. However, achieving high purity of reconstructed hyperons with high efficiency is...
Hypernuclei, bound states of nucleons and hyperons, serve as a natural laboratory to investigate the hyperon-nucleon ($Y$-$N$) interaction, which is an important ingredient for the nuclear equation-of-state. Furthermore, precise measurements of their production yields in heavy-ion collisions are crucial for understanding their production mechanisms. In addition, the strangeness population...
Antimatter in cosmic rays is a powerful probe for Dark Matter indirect de-
tection. To constrain the background from secondary antiparticles, produced
during cosmic ray propagation through the interstellar medium, the related cross
sections need to be precisely determined at accelerator facilities. In particular,
being their secondary production suppressed at low energies with respect...
Measurements of jet substructure in ultra-relativistic heavy ion collisions suggest that the jet showering process is modified by the interaction with quark gluon plasma. Modifications of the hard substructure of jets can be explored with modern data-driven techniques. In this study, we use a machine learning approach to identify jet quenching amounts. Jet showering processes, with and without...
The collective properties of nuclear structure, such as radii and deformations, leave distinct signatures in the initial and consequently final stages of relativistic heavy-ion collisions. Collisions of deformed nuclear enhance the fluctuations of harmonic flow coefficients $v_n$ and event-wise mean transverse momentum $[p_T]$, therefore offering a viable approach to establish clear...
The study of small collision systems at RHIC (pp, pA, dA, $^{3}$HeA, OO) and the LHC (pp, pPb, OO) provide crucial insights into the limits of quark-gluon plasma formation. Recently, we have analyzed new experimental results in terms of hydrodynamics, pre-hydrodynamics, decorrelations, and non-flow (Phys.Rev.C 105 (2022) 2, 024906). We extend these studies to include ultra-peripheral...
Previous applications of machine learning to jet background subtraction have shown improvements over the traditional background subtraction methods, especially at low jet momentum. While machine learning applications generally lead to improvements, care must be taken to ensure they are not at the cost of interpretability and bias from models used for training. We present a novel application of...
Heavy-quark hadrons are used to study the properties of the partonic stages of a heavy-ion collision, where a quark-gluon plasma medium is created. We are investigating charm quark production in and outside of jets via angular correlations of trigger hadrons and associated electrons from heavy-flavor hadron decays. As a first step, we are investigating the 5.02 TeV p-Pb collisions, where in a...
Studies have yielded strong evidence that a deconfined state of quarks and gluons, the quark--gluon plasma, is created in heavy-ion collisions. This hot and dense matter exhibits almost zero friction and a strong collective behavior. An unexpected collective behavior has also been observed in small collision systems. In this talk, the origin of collectivity in small collision systems is...
Jet quenching measurements in heavy-ion collisions, such as the suppression of the jet yield compared to pp collisions, aim to elucidate the various mechanisms of parton energy loss. Differential measurements of the dependence of the inclusive jet nuclear modification factor ($R_{\rm AA}$) on the jet resolution parameter ($R$) may help disentangle energy loss mechanisms and discriminate...
In this poster, we present the ATLAS measurement of the centrality dependence of the dijet per-event yield at center-of-mass energy 8.16 TeV in $p$+Pb collisions. The per-event yield of unfolded dijet pairs is presented in terms of kinematic variables that allow for full characterization of the partonic scattering system, i.e. the average $p_{\mathrm{T}}$ of the dijet, $p_{\mathrm{T,Avg}} =...
High-energy nucleus-nucleus collision experiments have played a crucial role in exploring high-temperature quark matter, such as the quark-gluon plasma (QGP). The study of various hadrons, characterized by diverse internal structures, constituent quark numbers, and quark species, has been essential for understanding QGP properties. It has become increasingly evident that hadron yields in...
The sPHENIX detector at the Relativistic Heavy Ion Collider (RHIC) is designed to study the small scale structure of the quark-gluon plasma (QGP) created in collisions of heavy ions. Jets, produced in hard scatterings early in the collisions, provide an ideal probe for the full evolution of the QGP. sPHENIX is the first detector at RHIC with full coverage electromagnetic and hadronic...
The jet quenching parameter $\hat q$ encodes jet medium interactions during the entire quark-gluon plasma evolution in heavy-ion collisions. For a long time, the impact of pre-equilibrium stages has not been properly treated in jet quenching calculations, although recent studies find large values for $\hat q$ in the earliest (glasma) stage. For the first time, we show that QCD kinetic theory...
The new sPHENIX detector at Brookhaven’s National Laboratory’s Relativistic Heavy Ion Collider (RHIC) was designed to significantly further the study of the nature of hot nuclear matter. The use of jets as a probe in p+A and A+A collisions allows access to the interaction of the hard-scattered partons with the nuclear environment and is sensitive to a wide range of scales. sPHENIX will use...
In high-energy nuclear collisions, the light nuclei production is sensitive to the temperature and density of the system at freeze-out. It is also predicted to be sensitive to local baryon density fluctuations and can be used to probe the QCD phase transition. The second phase of Beam Energy Scan (BES-II) program at RHIC was completed in 2021. The high-statistics data recorded by the STAR...
We present a Monte-Carlo implementation of the EKRT initial-state model (MC-EKRT) [1]. Our new MC-EKRT event generator is based on collinearly factorized, dynamically fluctuating pQCD minijet production, supplemented with a saturation conjecture that controls the low-$p_T$ particle production. Previously, the EKRT model has been very successful in describing low-$p_T$ observables at...
The mean $p_{\rm{T}}$ fluctuations in heavy-ion collisions can be related to temperature fluctuations which quantify the specific heat of the system. Any deviations from the Hadron Resonance Gas model as a function of the incident energy can be interpreted as a possible signal of criticality. In this poster we present the first efficiency corrected charged particle event-by-event mean...
Measurements of the production of heavy-flavour hadrons in proton–proton (pp) collisions provide an important test of quantum chromodynamics (QCD).The heavy-flavour production cross section can be calculated using the factorisation approach as a convolution of three factors: the parton distribution functions, the partonic cross section, calculated with perturbative QCD calculations, and the...
Measurements of charm baryon and meson production in pp and p–Pb minimum bias collisions and as a function of multiplicity, help to investigate hadronization processes and to study their modification across the collision systems from pp to Pb–Pb, and from low to high multiplicities.
Recent measurements of the fragmentation fractions of charm hadrons in pp and p–Pb challenge the universality...
Heavy quarks are produced at the very early stage of heavy-ion collisions, and they experience the whole evolution of the Quark-Gluon Plasma (QGP) created in these collisions. Measurements of the elliptic flow and nuclear modification factor of charmed mesons in heavy-ion collisions at RHIC and the LHC provide ample evidence of strong interactions between charm quarks and the QGP. However, a...
By comparing the particle production in pp and p--Pb collisions, nuclear initial state effects can be studied. Measurements of the $\omega$ meson $p_\text{T}$-spectra in pp and p--Pb collisions not only allow for a determination of the nuclear modification factor $R_\text{pA}$, but also provide insight into the fragmentation process and serve as vital input for direct-photon cocktail...
The properties of the Quark-Gluon Plasma (QGP) produced in heavy-ion collisions can be studied using jets generated in hard scattering processes at the early stages of the collision. These jets lose energy and have their shower structures modified relative to that in the vacuum due to jet-medium interaction — known as `jet quenching'.
The transverse momentum ($p_{\rm T}$) fraction of the...
Compared to $\rm{e^+e^-}$ and ep collisions, the charm baryon production in pp collisions shows a substantial enhancement. This evidence is currently interpreted in terms of a modification of the hadronization mechanisms in hadronic collisions. Therefore, valuable information on how the charm quarks hadronize can be studied by measuring charm baryon production. In addition, by sorting out the...
$J/\psi$ serves as an important probe to study the properties of the quark-gluon plasma (QGP) created in heavy-ion collisions. In Ru+Ru and Zr+Zr collisions at $\sqrt{s_{NN}} = 200$ GeV, it has been observed that the $J/\psi$ yield is strongly suppressed and its elliptic flow ($v_{2}$) is consistent with zero, indicating $J/\psi$'s strong coupling with the medium and its potentially small...
Two-particle correlation analyses are often used to study the spatial and temporal extension of particle-emitting source in high-energy nuclear collisions. Precise information on the final state interactions amongst the particles under study can also be extracted from the measurement. It is particularly interesting to study the energy dependence of the extracted source size at the moment of...
Jets are collimated sprays of hadrons fragmented by highly virtual partons produced in the early stage of heavy-ion collisions via hard scatterings. Different observables of the jet-medium interaction probe the properties of the Quark-Gluon Plasma and its dynamics. The bulk medium produced in non-central heavy-ion collisions is expected to be tilted with respect to the beam axis, while the...
Studying heavy flavor can enhance our comprehension of parton interactions with the Quark-Gluon Plasma (QGP). Due to their significant mass, heavy quarks (charm and bottom) are mainly generated during the initial phase of high-energy heavy-ion collisions when hard scatterings are prevalent, and experience the entire evolution of the QGP. One way to study the production of heavy quarks is...
Particle production in ultra-relativistic pp collisions can be factorized into the parton density function (PDF), the partonic cross-section and the fragmentation function (FF). FFs need to be constrained by experimental data for each particle species. Measurements of the momentum fraction $z$ of a particle species contained in a high energetic jet give direct access to the FF of the...
The production of hadrons containing charm or beauty quarks in pp collisions provides an important test for quantum chromodynamics calculations. These measurements also serve as reference for more complex systems such as Pb--Pb collisions, helping to characterize the various in-medium partonic energy loss mechanisms and their dependence on the quark mass.
The excellent particle...
Quarkonia play a unique role in probing the properties of the quark-gluon plasma (QGP). The dissociation of quarkonia due to the color screening was proposed as a direct signature of the QGP formation. On top of that, different states of quarkonium are expected to dissociate at different temperatures depending on their binding energies. Therefore, measurement of the expected sequential...
Measurement of the jet substructure and the distribution of final state hadrons within a jet provide a detailed look into both the partonic shower and hadronisation process. These processes can be studied using the transverse momentum ($j_\mathrm{T}$) and longitudinal momentum fraction ($z$) of constituent particles. ALICE has recently measured the transverse momentum distributions of the jet...
Energetic partons lose energy in the quark-gluon plasma (QGP) and then fragment and hadronize into showers of particles called jets. Measurements of the internal structure of these jets can constrain how energetic partons interact with the QGP. Though species-independent jet substructure measurements have made much progress recently, a complete understanding of the identified particle...
The ALICE detector at the CERN LHC is particularly suited to study light (anti)nuclei produced in high-energy collisions between hadrons. The formation mechanism of (anti)nuclei in these collisions is still one fundamental open question that is being addressed both theoretically and experimentally. This mechanism is investigated by comparing experimental data with phenomenological models such...
The initial QGP geometry of the quark-gluon plasma (QGP) is manifested as azimuthal anisotropy in final state particles of a nuclear collision in the plane transverse to the beam direction. This study measures the Fourier coefficients $v_{2}$ and higher order harmonics of charged particle distribution in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with 2018 data collected by the...
Relativistic heavy-ion collisions generate extremely strong electromagnetic fields, providing an ideal environment to study the electromagnetic excitation of the vacuum. Furthermore, the electromagnetic fields are sensitive to the charge distributions of the colliding nuclei which can be used to study the nuclear structure. The Breit-Wheeler process, the lowest-order decay mode of the QED...
Quarkonium production in high-energy proton-proton (pp) collisions is an important tool for studying perturbative and non-perturbative aspects of quantum chromodynamics (QCD) calculations. Charmonia are bound states of charm and anti-charm quark pairs. Their production process can be factorized into two stages: the heavy quark production and the formation of the bound state. The former...
Hard partonic scatterings, occurring at the early stages of heavy-ion collisions, produce jets, which experience the full evolution of the quark-gluon plasma (QGP). As they traverse through the QGP, jets lose energy through collisional and radiative processes, collectively known as the jet quenching. In semi-central heavy-ion events, the QGP takes an approximately elliptical shape in the...
Measurements of long-range angular correlations are one of the important tools to evaluate the interplay between the initial- and final-state effects in small collision systems in view of understanding the evidence of collectivity.
The charged-particle multiplicity distribution as a function of pseudorapidity ($\eta$) is asymmetric in p--Pb collisions. Since the mean free path depends on...
Two-particle correlation analyses are often used to study the spatial and temporal extents of the particle-emitting source in high-energy nuclear collisions. Information on the final state interactions amongst the particles under study can also be extracted from the measurement. For example, from the p-$\Lambda$ and p-$\Xi^-$ correlation functions, one could study the hyperon-nucleon (Y-N)...
In non-central Heavy-Ion collisions, a large orbital angular momentum is produced. A part of the orbital angular momentum can polarize the quarks and anti-quarks, hence the vector mesons, inside the medium. Recently, STAR measured the global spin alignment of φ(1020) mesons in Au+Au collisions from the first phase of the RHIC Beam Energy Scan I (BES I) program [1].
The global spin...
Hard-scattered partons ejected from high-energy collisions undergo fragmentation and hadronization, resulting in collimated sprays of particles that are clustered into jets. The Energy-Energy correlator (EEC) is a jet substructure observable used to study the time evolution of the parton shower. This observable re-contextualizes jet substructure study by using the distribution of angular...
When a jet injects energy and momentum into a droplet of QGP, it generates a wake that, after the QGP hadronizes, results in the creation of soft and semi-hard particles correlated with the jet direction. This medium response phenomenon plays a crucial role in describing various jet observables, as demonstrated by many jet quenching studies. However, the computational complexity of current...
Quarkonia have been long considered as key features in heavy ion collision to study the properties of the quark-gluon plasma. One of the key signatures is the sequential yield suppression for different quarkonium states in nucleus-nucleus (A+A) collisions compared to p+p collisions following the ordering of their binding energies. Moreover, sequential yield modification has also been observed...
We study the critical point effects on particle number fluctuations both in the crossover ($T > T_{\rm c}$) and mixed phase ($T < T_{\rm c}$) regions by means of molecular dynamics simulations of a Lennard-Jones fluid, motivated by the ongoing search for the QCD critical point in heavy-ion collisions.
In the crossover region, we find large fluctuations associated with the critical point in...
Large-$N_c$ QCD implies a duality between confined baryons and deconfined quarks at high baryon densities; it is called Quarkyonic matter. We present a model of Quarkyonic matter that is explicitly dual between quarks and baryons. The duality means that the free energy of the matter is expressed in two ways: One is as a functional of the quark distribution function in the momentum space,...
The Compressed Baryonic Matter (CBM) experiment at FAIR will investigate the QCD phase diagram at high net-baryon densities ($μ_B$ > 500 MeV) with heavy-ion collisions in the energy range $\sqrt{s_{NN}} = 2.9−4.9$ GeV. Precise determination of dense baryonic matter properties requires multi-differential measurements of strange hadron yields and their collective flow, both for the most...
Event classifiers based either on the charged-particle multiplicity or on event topologies, such as spherocity and Underlying Event, have been extensively used in proton-proton (pp) collisions by the ALICE Collaboration at the LHC. These event classifiers became very useful tools since the observation of fluid-like behavior in high multiplicity pp collisions, for example radial and anisotropic...
Studying quarkonium production allows us to probe the properties of strongly interacting matter, such as the quark-gluon plasma and the gluonic matter in heavy nuclei. While such a probe is widely used, a complete understanding of the quarkonium production mechanism is not yet achieved, even for $p$+$p$ collisions. Therefore, quarkonium studies in $p$+$p$ collisions are essential for advancing...
Recent measurements of the baryon-to-meson production yield ratios between charm baryons ($\Lambda_\mathrm{c}^{+}$, $\Sigma_\mathrm{c}^{0,++}$, $\Xi_\mathrm{c}^{0,+}$, $\Omega_\mathrm{c}^{0}$) and $\mathrm{D}$ mesons ($\mathrm{D}^0$) in small collision systems show a significant enhancement with respect to the measurements performed in $e^{+}e^{-}$ collisions. These results were compared with...
In nucleus-nucleus collisions at LHC energies, a deconfined state of matter, the quark-gluon plasma (QGP), is formed. Generally, proton-proton (pp) collisions are used as a reference to study their fundamental properties. However, at the highest energy reached in LHC Run 2, pp collisions at high multiplicity seemed to exhibit signatures of collective phenomena similar to those observed in...
Constraining the three-dimensional structure of the initial state and transport properties of the Quark-Gluon Plasma (QGP) at different temperatures ($T$) and baryon chemical potentials ($\mu_B$) is a critical objective of heavy-ion programs at RHIC and the LHC. This work presents comprehensive measurements on both topics for various event-shape and centrality selections of Au+Au collisions at...
Two particle femtoscopy provide a powerful tool for studying the space–time dynamics of the hot and dense matter (QGP) created in these collisions such as the size, shape, and lifetime as well as advancing our understanding of the behavior of matter at extreme conditions by measuring the relative momentum correlations between pairs of particles emitted in the same direction from the collision....
We perform a non-perturbative calculation of quarkonium dissociation rates in the quark-gluon plasma (QGP) within a thermodynamic T-matrix approach. The latter resums an infinite series of ladder diagrams for heavy-light interactions appropriate for a strongly coupled QGP which are implemented via half-off-shell amplitudes accounting for recoil corrections and interference effects (related to...
The study of the production of non-prompt ${\rm J/\psi}$ originating from the decay of beauty hadrons, besides allowing to isolate the prompt ${\rm J/\psi}$ cross section from the inclusive ${\rm J/\psi}$ cross section, can be used to estimate open beauty-hadron production. Heavy-flavour particle production in pp collisions as a function of charged-particle multiplicity could provide insight...
One of the most pressing questions in both hot and cold QCD communities is what the physics mechanism responsible for modified parton densities in heavy nuclei is. One promising channel to address this question is the photoproduction of vector mesons, which is considered a clean probe to the nuclear parton structures.
We present a measurement of $\pi^+\pi^-\pi^+\pi^-$ photonuclear...
Collective flow is observed in high-energy proton-proton and proton-nucleus collisions where particle multiplicities are small and a quark-gluon plasma description is hard to justify. Here, we address the origin of such observations from a new angle, by performing an experimental investigation of the emergence of hydrodynamics in two-dimensional ultra-cold Fermi gases with with controllable...
Ultraperipheral nucleus-nucleus collisions produce very large photon fluxes such that fundamental quantum-mechanical processes can be observed and studied in a novel way. In this presentation, an observation of the $\tau$ lepton photoproduction at LHC is reported, using ultraperipheral lead-lead collision data collected by CMS. This measurement paves the way for a precise determination of the...
On the gravitational wave emission in the magnetic field
of a heavy-ion collision
In the classic 1961 paper of Gertsenshtein [1] he demonstrated that an electromagnetic wave can be transformed into a gravitational wave when propagating through an external, transverse magnetic field. Later in 1973, Zel’dovich calculated the fraction of energy of the electromagnetic wave transformed into the...
The ePIC detector is being designed as a hermetic, general-purpose detector for the Electron-Ion Collider (EIC). One of the key performance drivers for the physics programme at the EIC are the particle identification (PID) system, which enable the separation of pions, kaons, and protons in high multiplicity events over a wide phase space, with significant pion/electron suppression. To address...
The simple picture of a hard scattering per $p+p$ collision has been challenged by several measurements performed at LHC and RHIC, revealing a more complex dynamics of multiple parton interactions (MPI) which are essential to fully understanding particle production in hadronic collisions. Hard probe measurements at different particle multiplicity regimes in $p+p$ collisions provide a clean...
Jet quenching parameter $\hat{q}$ is essential for characterizing the interaction strength between jet partons and nuclear matter. Based on the quark-meson (QM) model, we develop a new framework for calculating $\hat{q}$ at finite chemical potentials, in which $\hat{q}$ is related to the spectral function of the chiral order parameter. A perturbative calculation up to the one-loop order...
The $B^\pm$ meson is produced more frequently than any other meson containing beauty quarks in pp collisions at the LHC. Measuring its production cross-section is important for two reasons. Firstly, it allows for testing perturbative quantum chromodynamics calculations. Secondly, it provides an essential reference for measurements of its nuclear modification factor ($R_{\rm A \rm A}$) in...
Identified hadrons have proven to be useful in elucidating the final state effects of heavy ion collisions. This includes in particular the important role that hadronization plays on a variety of final state observables. System size is known to influence various observables, and the overlap in system size between different collision systems has helped establish the commonality between them,...
Central exclusive production (CEP) is a diffractive process in which the colliding particles remain intact. Three different processes are involved: photon-photon exchange, photon-pomeron exchange and double-pomeron exchange. Each process produces distinguishable states with specific sets of quantum numbers, making CEP measurements a unique tool for searching for exotic resonances. Furthermore,...
We study the contribution to the equation of state from mesonic correlations in the Polyakov-loop Nambu--Jona-Lasinio model within the Beth-Uhlenbeck approach, with a focus on the spacelike region of the spectral function. We show that the inclusion of such excitations leads to a significant increase of the pressure of the model near the pseudocritical temperature of the chiral phase...
With the newly upgraded sPHENIX detector capable of performing high precision jet substructure measurements, we present a comprehensive and systematic jet substructure study at the Relativistic Heavy Ion Collider. The study includes a variety of key jet substructure variables such as jet angularities with and without soft-drop or collinear-drop grooming, as well as recoil-free di-jet and...
Two-particle number and transverse momentum correlations are sensitive probes of particle production and transport in AA collisions. Their shape and strength are sensitive to the interplay of all production processes, and are further influenced by transport mechanisms, including longitudinal, radial, and anisotropic flow. However, the correlations are also sensitive to instrumental effects,...
We have probed the effect of the nonextensivity on the transport properties related to the charge and heat in hot QCD medium at finite magnetic field and chemical potential. The coefficients associated with the charge and heat transport, such as the electrical conductivity, Hall conductivity, thermal conductivity and Hall-type thermal conductivity are determined using the nonextensive Tsallis...
Charge balance functions (BFs) were introduced at the beginning of the RHIC era as a tool to investigate the evolution of particle production in heavy-ion collisions and identify the presence of delayed hadronization as an indicator of the formation of long lived isentropic expanding quark gluon plasma in high-energy nucleus-nucleus (A--A) collisions. It later emerged that BFs are rather...
The study of event-by-event fluctuations of the mean transverse momentum, $\langle p_{\rm{T} }\rangle$, could probe the nature of the phase transition and seek evidence for temperature fluctuations. In this talk, event-by-event $\langle p_{\rm{T} }\rangle$ and higher order fluctuations of charged particles produced in pp collisions at $\sqrt{s}=5.02$ TeV, Xe--Xe collisions at...
Two-particle transverse momentum correlator $G_{2}$ was measured based on data collected from Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76\;\text{TeV}$. The evolution of the longitudinal width of the $G_{2}$ correlator vs. collision centrality nominally provides information about the specific shear viscosity, $\eta/s$, of the medium formed in the collisions. The $G_{2}$ correlator was also...
The strangeness content of the final state in ultrarelativistic heavy ion collisions has been studied through measurements of kaons, Λ, Ξ and Ω baryons in pp, pA and AA collisions. $\Sigma$ baryons contain a single strange quark and form a triplet, with the charge (+, 0, -) depending on the light quark content. In a thermal model scenario, these states are abundant enough to carry a...
Measurements of high-multiplicity pp and pA collisions at LHC energies have revealed that these small collision systems exhibit some quark-gluon plasma-like features, such as collective behaviour and strangeness enhancement, formerly thought to be achievable only in nucleus-nucleus collisions. A proposed method to narrow down the origin of these phenomena is to study the effect of MultiParton...
Light-flavor hadrons constitute the bulk of the particles produced in high energy hadronic collisions at LHC. Recent studies show that in high multiplicity pp and p—Pb collisions at LHC energies, particle production exhibits features that mimic the behaviors observed in AA collisions (e.g., mass-dependent pT hardening and strangeness enhancement). These features are a typical sign of the...
The sequential clustering of particles into jets offers an algorithmic connection of hadrons to the partons of the radiation shower. Jet substructure allows us to access the radiation history of a jet thereby providing a useful avenue to probe QCD through different energy scales. The N-point Energy Correlator (ENC) is a recently proposed observable that highlights this feature of jets as a...
The production of light (anti)nuclei in high-energy hadronic collisions has been studied in depth with the ALICE experiment at the LHC. Despite this, the production mechanism of light (anti)nuclei is still not well understood and remains a highly-discussed topic in the scientific community. One of the phenomenological models typically used to describe the hadronization process is the...
The NA60+ experiment, proposed for data taking in the next years, aims to investigate the high baryochemical potential region of the QCD phase space diagram, exploiting the large intensity of CERN SPS beams.
NA60+ will have the possibility to access the high $\mu_{B}$ region of the QCD phase diagram, by studying rare probes via a beam-energy scan with PbPb and p-A collisions in the...
Correlation function of baryons has been used in heavy-ion collisions to study the space-time structure, the dynamical evolution of the particle-emitting source, and final state interactions.
In this poster, we will present correlation functions of protons in Au+Au collisions at $\sqrt{s_{NN}}$ = 3.2 GeV from the second phase of the beam energy scan (BES-II) at STAR. The Lednicky-Lyuboshitz...
The pseudorapidity density of charged particles with different values of minimum transverse momentum ($p_\mathrm{T}$) thresholds of 0.15, 0.5, 1, and 2 GeV/c is measured in pp collisions at $\sqrt{s} =$ 5.02 and 13 TeV with the ALICE Run 2 set-up. The study is carried out for inelastic collisions with at least one primary charged particle having a pseudorapidity ($\eta$) within ±0.8 and...
Chiral symmetry is lost at low temperatures, and pions are massless in the chiral limit; there is no longer any screening mass. The screening mass of mesons approaches the standard value of $2 \pi T$ at high temperatures. The screening masses of mesons provide a gauge invariant and definite order parameter of chiral symmetry restoration. Different mesonic correlation lengths for flavor...
Quarkonia measurements in heavy-ion collisions are important for understanding both initial-state effects on heavy-quark production and final-state interactions between heavy quarks and the hot and dense nuclear matter created in high-energy heavy-ion collisions.
The sPHENIX experiment at RHIC will begin its commissioning and first Au+Au data-taking run in 2023, and plans to measure the...
We examine in detail the mass, lifetime and spin structure of quarkonium in a rotating vortical medium, where the quark spin is not necessarily aligned with the vortex.
After justifying this set-up in terms of spin hydrodynamics, and outlining the expected dependence of spin and vorticity, we examine the mass, lifetime and spin density matrix of quarkonium.
Our analysis implies a novel...
Quarkonium production in high-energy hadronic collisions is sensitive to both perturbative and non-perturbative aspects of quantum chromodynamics (QCD) calculations. Indeed, the production of the heavy-quark pair is described by perturbative QCD while the formation of the bound state is a non-perturbative process, treated in different ways by available theoretical models. Quarkonium...
In ultra-relativistic heavy-ion collisions, strong electromagnetic fields arising from the Lorentz-contracted, highly charged nuclei can be approximated as a large flux of high-energy quasi-real photons that can interact via the Breit-Wheeler process to produce $e^{+}e^{-}$ pairs. The collision energy dependence of the cross section and the transverse momentum distribution of dielectrons from...
The transport properties of the quark-gluon plasma, which is produced in heavy-ion collisions, provide crucial information about quantum chromodynamics (QCD). Bayesian analysis has been highly effective in constraining QCD matter properties [1, 2]. When combined with additional flow observables, LHC Pb-Pb data at 5.02 and 2.76 TeV have significantly reduced the uncertainties [2]. However, our...
Collisions of small systems show signatures suggestive of collective flow associated with QGP formation in heavy-ion collisions. Jet quenching is also a consequence of QGP formation, but no significant evidence of it in small systems has been found to date. Measuring or constraining the magnitude of jet quenching in small systems is essential to determine the limits of QGP formation. The ALICE...
A crucial component to the Electron Ion Collider (EIC) program is the collider luminosity, with a target absolute (relative) uncertainty of less than 1% (exceeding 10⁻⁴ in precision). The luminosity determination will be achieved employing two complementary approaches, one by direct detection of bremsstrahlung photons and another using a Pair Spectrometer (PS) which utilizes e+e- conversions...
The sPHENIX experiment is comprised of two layers of hadronic calorimeters (HCal). The outer HCal is the outermost layer located outside the solenoid coil, and the inner HCal is positioned between the solenoid magnet and the Electromagnetic Calorimeter. The sPHENIX program, aimed at achieving precise jet measurements and analyzing the microscopic properties of the strongly interacting...
The sPHENIX experiment has achieved a major milestone with the construction and installation of the cutting-edge three-layer Monolithic-Active-Pixel-Sensor (MAPS) based VerTeX detector (MVTX) in April 2023, in preparation for first beam in Spring 2023. The MVTX is the innermost tracking detector, boasting a spatial resolution of 5 $\mu$m and covering 2.5-4.0 cm radially, and a pseudorapidity...
We explain how spin alignment of vector mesons can be induced by background color fields. Our study is based on the quantum kinetic theory of spinning quarks and antiquarks and incorporates the relaxation of the dynamically generated spin polarization. The spin density matrix of vector mesons is obtained by quark coalescence via the Wigner function and kinetic equation. Our approach predicts a...
Transverse Λ polarization observed over four decades ago contradicted expec-
tations from early leading-order perturbative QCD calculations. Measurements
of Λ polarization from unpolarized pp and pA collisions have been previously
observed to increase as a function of xF and pT up to a few GeV range and
approximately independent of beam energy. Recent studies have linked polar-
ization to...
The validity of the Statistical Hadronization Model (SHM) has been successfully tested to adequately reproduce hadronic particle abundances over nine orders of magnitude in high energy collisions of heavy ions. Assuming a thermally equilibrated system, experimental particle yields at RHIC and the LHC serve as an anchor for the determination of common freeze-out parameters in the QCD phase...
Higher-order fluctuations of the net-proton number distributions in heavy-ion collisions are expected to be sensitive to a QCD critical point. These fluctuations can be obtained by measuring various order of cumulants, $C_n$, of the net-proton multiplicity distributions. The collision energy dependence of net-proton $C_4/C_2$ from Beam Energy Scan I hints at a possible enhancement from...
The ratio between (multi-)strange and non-strange hadron yields increases with the multiplicity of charged particles produced in hadronic collisions, revealing a smooth transition from low multiplicity pp collisions to central Pb-Pb collisions. The microscopic origin of this behaviour, known as strangeness enhancement, has yet to be understood. The data collected by the ALICE experiment during...
The production of strange quarks and antiquarks in high-energy collisions of
heavy ions is a significant indicator for the creation of a state of matter known
as Quark-Gluon Plasma (QGP). The QGP is characterized by the liberation of
quarks and gluons from their confinement inside hadrons. Due to their prompt
decay via weak interactions, strange quarks and antiquarks are not present...
Strangeness production is considered a sensitive probe to the properties of the medium created in heavy-ion collisions. The RHIC Beam Energy Scan Program (BES) is designed to investigate the QCD phase diagram and search for a potential QCD critical point. The BES-program covers a wide energy range from $\sqrt{s_{\rm{NN}}}$ = 3 to 54.4 GeV. Of particular interest is the high baryon density...
Neutron star equations of state that can sustain heavy neutron stars over 2 Msun necessitate a large, rapid rise in the speed of sound. The family of equations of states, which assume electric neutrality along beta equilibrium and vanishing temperatures, with large bumps in the speed of sound have been suggested to be incompatible with the equation of state extracted from heavy-ion...
$K_{1}$ and $K^{*}$ mesons are chiral partners whose vacuum widths are smaller than 100 MeV. This makes these mesons ideal to study possible effects of chiral symmetry restoration in heavy-ion collisions. In a recent theoretical study, the $K_{1}/K^{*}$ ratio in heavy-ion collisions is expected to be substantially larger than the statistical hadronisation model predictions. The study of the...
Studies of gluon fragmentation at LEP have shown hints that gluon-initiated jets produce more baryons than quark-initiated jets. Our current knowledge of fragmentation functions is almost exclusively based on fits to data from $e^+ e^-$ collisions and semi-inclusive deep inelastic scattering processes, both of which are mainly sensitive to quark fragmentation, leaving gluon fragmentation...
In nuclear collisions at low RHIC energies, although $s$ and $\bar{s}$ quarks are produced in pairs, there is a significant excess of $\Omega^{-}$ over ${\bar{\Omega}}^{+}$ which suggests that $\Omega^{-}$ carries a net baryon number. Such an excess of net baryon number at mid-rapidity in Au+Au collisions manifests effective mechanisms of baryon number transport over a large rapidity gap....
Short-lived resonances are ideal probes to study the properties of the hadron gas phase created in heavy-ion collisions in the post-hadronization phase. Since the resonance lifetime is comparable to that of the hadron gas phase, their yields are affected by the competing rescattering and regeneration effects. These can be studied experimentally by measuring the yield ratio of resonances to the...
Two-particle correlation functions give insight into the microscopic details of the production and transport mechanisms of conserved quantum numbers. In this contribution, new final measurements by the ALICE Collaboration of $\Xi-\pi$, $\Xi-$K, $\Xi-$p, $\Xi-\Lambda$, and $\Xi-\Xi$ correlation functions are presented to study how charge, strangeness, and baryon numbers are balanced in...
We present a new experimental method to study three-body nuclear systems by measuring correlations in the momentum space of deuteron-hadron pairs produced in proton-proton collisions at the LHC. The study of three- and many-body dynamics has been a long-standing goal in nuclear physics, particularly for understanding the structure of light nuclei and describing neutron-rich and dense nuclear...
Fluctuations of conserved charges, such as baryon number, electric charge, and strangeness, are a unique tool for studying the phase diagram of strongly interacting matter. The cumulants of the distributions of the conserved charges in heavy-ion collisions can be related to the equation of state in lattice QCD (LQCD), making first-principles calculations accessible in the experiment. Recent...
Angular correlations and polarization studies provide valuable insights into the vector meson production mechanism, including interference effects as well as information on the nuclear geometry of the target. In this talk, we present two new results. We will report the first measurement of the polarization of both coherent and incoherent J/psi photoproduction in ultra-peripheral Pb--Pb...
We present a new model for jet quenching via coherent gluon radiation and elastic scatterings off medium partons. The jet energy loss is simulated as a perturbative final-state vacuum parton shower followed by a medium-induced shower originating from elastic and radiative collisions with the medium constituents. Coherency is achieved by starting with trial gluons that act as field dressing of...
The study of the suppression of the leading two hadrons within jets, by virtue of being robust against the underlying event background, provides an insight into the onset of quenching in the history of the evolution of relativistic heavy-ion collisions, which can help discriminate between different partonic energy loss mechanisms. The modification of their flavor correlations, on the other...
In studies of QGP, it has been observed that at high-energy heavy-ion (A$+$A) collisions, high-momentum particles with light and heavy flavors receive significant suppression. This indicates that particles lose their energies in QGP. One of the most important topics is to quantify the energy loss and to investigate the energy loss mechanism.
PHENIX measured the fractional momentum loss,...
We discuss the reconstruction of target jet and the framework of quantifying its internal substructure. Due to momentum and charge conservation, target and current correlation can be exploited which significantly constrains the event-wide particle distributions. We demonstrate this method using Pythia simulations of electron-proton collisions in the context of determining the flavor and...
In the exploration of the nuclear matter phase diagram, the susceptibilities of conserved charges are useful theoretical tools to probe the existence of a $1^\text{st}$ order phase transition, and a possible critical endpoint. They can be related to the cumulants of the considered net-charges, for which STAR collaboration recently published experimental measurements of proxies, in Au-Au...
In heavy ion collisions, the measured spectrum of direct photons at RHIC and the LHC has been found as azimuthally anisotropic as pions. In particular, a large elliptic flow of the direct photos has been observed, which strongly contradicts conventional theoretical predictions, leading to the well-known “direct photon puzzle”.
In this talk, instead of a strong magnetic field assumption...
Despite the success of hydrodynamic models in describing heavy-ion collisions, there have long been questions about its regime of validity. Recently-derived conditions on the causality of the hydrodynamic equations [1] can give a concrete answer --- if evolution is acausal, it is not a faithful representation of the underlying QCD theory. It is now known that current simulation models reach...
We employ the AdS/CFT correspondence to study the jet quenching effect in Quark-gluon plasma in heavy-ion collisions.The nuclear modification factor $R_{AA}$ and elliptic flow parameter $v_{2}$ are studied in different-centrality collisions at RHIC and LHC.Our numerical results agree with data.Magnetic field and chemical potential of the medium are also considered for the observable...
Understanding the modification of jets and high-p_T probes in small systems requires the integration of soft and hard physics. We present recent developments in extending the JETSCAPE framework to build an event generator, which includes correlations between soft and hard partons, to study jet observables in small systems. The multi-scale physics of the collision is separated into different...
The method of moments has been employed to derive relativistic fluid-dynamical theories from the Boltzmann equation for the past decades [1]. This approach consists in expanding the single-particle distribution function using a basis of irreducible momenta, where the expansion coefficients are the irreducible moments of the nonequilibrium distribution function [2]. Unlike the Chapman-Enskog...
The study of strongly interacting matter under external conditions (such as high temperatures and/or baryon densities) provides unique insights into its fundamental theory, Quantum Chromodynamics (QCD). A nonzero angular momentum imposed on a QCD system can bring rich and intriguing phenomena, with the proton spin structure being a perfect example. A much larger QCD system with substantial...
The shear viscosity (eta) of a quark-gluon plasma in equilibrium can be calculated numerically using the Green-Kubo relation or analytically using several methods, including the Israel-Stewart, Navier-Stokes, relaxation time approximation, and Chapman-Enskog methods. In this work [1], we first examine these analytical methods for isotropic as well as anisotropic two-body scatterings. We...
Experiments at the future Electron-Ion collider pose stringent requirements on the tracking system for the measurement of the scattered electron and charged particles produced in the collision, as well as the position of the collision point and any decay vertices of hadrons containing heavy quarks. Monolithic Active Pixel Sensors (MAPS) offer the possibility of high granularity in combination...
The sPHENIX detector is the next generation experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. Starting commissioning in May, it will collect high statistics data sets from ultra relativistic Au+Au, p+p and p+Au collisions in the next 3 years. The readout is a combination of triggered readout for calorimeters and streaming readout for the silicon...
When studying the properties of the Quark-Gluon Plasma (QGP) formed in relativistic heavy ion collisions, it is necessary to classify the events based on the size and shape of the QGP. Typically, events are categorized by mapping the impact parameter, which cannot be measured directly, to a bulk observable that varies monotonically with it, such as soft particle production. In the mapping,...
Recent experimental results present collectivity also in small systems with high-multiplicity. Today these phenomena are not completely understood: it is an important question whether the presence of the QGP is necessary for the observed collectivity or not. Moreover, the connection between the experimental observables and theories is not trivial. In our phenomenological study we introduce the...
Universality is omnipresent when certain classes of microscopic theories are coarse-grained into effective macroscopic descriptions. Hydrodynamic theories are such macroscopic descriptions in long-wavelength, low-frequency limits of many quantum field theories. On the phenomenological side, hydrodynamics not only serves as a successful macroscopic description of the Quark-gluon plasma (QGP) in...
Dielectrons are an exceptional tool to study the evolution of the medium created in heavy-ion collisions. In central collisions, the energy densities are sufficient to create a quark-gluon plasma (QGP). Thermal e$^{+}$e$^{-}$ pairs with invariant masses around 1.5 GeV/$c^{2}$ can be used to estimate the early average temperature of the QGP.
At LHC energies, the cross section of...
The question of identifying the baryon topological structure encoded in the baryon junctions has a long history and was recently addressed in the measurements of baryon stopping by the STAR collaboration. We suggest considering this question in a simple, exactly solvable model that allows us to clearly separate the topological junction structure from the valence quarks. We find that baryon...
The sPHENIX detector at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) has a broad experimental QCD physics program focused on jets, their substructure, and open and closed heavy flavor production. To measure these observables, the sPHENIX tracking system is composed of a silicon vertex and strip detector, continuous-readout time projection chamber, and...
The tracking reconstruction procedure for the sPHENIX experiment combines data from its silicon pixel detector, silicon strip detector, time projection chamber, and micromegas-based outer tracker modules to produce tracks that trace a given particle's path through 57 total sensor layers. After clustering of the raw data is completed, the track seeding modules identify chains of clusters that...
We discuss the transport coefficients of heavy quarkonia moving in high temperature QCD plasmas. The thermal width and mass shift for quarkonia are closely related to the momentum diffusion coefficient and its dispersive counterpart for heavy quarks, respectively. For quarkonium at rest in plasmas, the longitudinal gluon part of the color-singlet self-energy diagram is sufficient to determine the...
We present a new study of two-particle correlations as extracted with the CMS experiment in 8.16 TeV proton-lead (pPb) events with large rapidity gaps in the proton going region. Recent comparisons of the cross sections of such events measured in CMS as a function of the rapidity gaps (i.e., regions devoid of any particle activity) with several generators suggest that such events have...
We investigate how the event-by-event fluctuations of the final-state distribution function of nucleons physically affect the yield ratio of light nuclei based on the coalescence model.
The yield ratio of light nuclei, $N_tN_p/N_d^2$ (with $N_t$, $N_p$, and $N_d$ being triton, proton, and deuteron numbers, respectively) [1,2], is one of the observables suggested for a possible signal of the...
The Ridge behavior in high-multiplicity proton-proton collisions has been discussed a lot since it was first reported. However, small systems like proton-proton collisions are not enough to generate a medium called Quark-Gluon Plasma (QGP) in which the Ridge behavior is explained with high-order flows. In this work, we suggest the pure kinematic mechanism between jets and medium partons as...
Experimental data on a wide range of jet observables measured in heavy ion collisions provide a rich picture of the modification of jets as perturbative probes and of the properties of the quark-gluon plasma. However, their interpretation is often limited by the assumptions of specific quenching models, and it remains a challenge to establish model-independent statements about the universality...
Rare probes such as jets and heavy flavor hadrons provide unique opportunities to study the short-distance scale properties of the QGP created in heavy ion collisions. For example, recent measurements at the LHC and RHIC indicate that jet energy loss is correlated with the distance traveled through the QGP medium, and as a result, the initial geometry of the QGP. While estimates of...
Nowadays, relativistic dissipative hydrodynamics including effects of finite viscosities is commonly used to extract transport properties of the quark gluon plasma (QGP), such as shear viscosity and bulk viscosity, from experimental data. However, according to the fluctuation-dissipation relation (FDR) in non-equilibrium statistical physics, fluctuations and dissipation are always accompanied...
Investigating particle production in small systems has become instrumental
in probing non-perturbative contributions to hadron structure and hadroniza-
tion mechanisms. The LHCb spectrometer unique geometry at the LHC along
with its particle identification and tracking capabilities allow for new studies
of the multiplicity-dependent enhancement of strange hadrons in the forward
region....
Understanding the strong interaction between nucleons and hyperons is fundamental for the microscopic description of bound systems as well as for modeling the equation of the state of dense stellar objects, such as neutron stars. Conventional scattering and hypernuclei measurements are insufficient to support theoretical predictions about the interaction between hadrons containing strangeness....
The sPHENIX project is a new detector experiment at the Relativistic Heavy Ion Collider at BNL. Its aim is to study strongly interacting Quark-Gluon Plasma and cold-QCD by measuring photons, jets, jet correlations, and Upsilon family with high precision. To achieve these goals, a precise tracking system is necessary. The tracking system of the sPHENIX detector consists of the MVTX, TPC, TPOT,...
