The ALICE Collaboration has proposed a completely new apparatus, ALICE 3, for the LHC Run 5 (LoI, arXiv:2211.02491). The detector consists of a large pixel-based tracking system covering eight units of pseudorapidity, complemented by multiple systems for particle identification, including silicon time-of-flight layers, a ring-imaging Cherenkov detector, a muon identification system, and an...
We present new lattice results for the heavy quark diffusion coefficient in 2+1 flavor QCD in the temperature range from 163 MeV up to few GeV. Compared to previous lattice calculations with unphysical light quark masses, we consider near-physical values and a much wider temperature range. Our results for the spatial heavy diffusion coefficient near the crossover temperature are considerably...
In heavy-ion collisions, jets formed from hard-scattered partons experience an overall energy loss and have a modified internal structure compared to vacuum jets. These modifications are a result of the interactions between the energetic partons in a jet shower and the strongly coupled quark-gluon plasma (QGP). As the jet traverses the QGP, it loses momentum to the medium, which in turn...
In non-central heavy ion collisions, substantial angular momentum is generated, resulting in significant vorticity and the spin polarization of particles with finite spin along the global angular momentum. Additionally, anisotropic flow can produce local vorticities in both in-plane (z) and out-of-plane (y) directions, leading to local polarization. The RHIC Beam Energy Scan II (BES-II)...
The LHCb detector’s forward geometry provides unprecedented access to
the very low regions of Bjorken \textit{x} inside the nucleon. With full particle ID and a fast DAQ, LHCb is able to fully reconstruct plentiful charged particles and neutral mesons, as well as relatively rare probes such as heavy quarks, providing a unique set of constraints on nucleon structure functions. This...
The second-order shape phase transition of the Xe isotope chain, predicted to lie around $^{128}\text{Xe}$ to $^{130}$Xe, is challenging to measure in low-energy nuclear experiments. Recently, heavy-ion collisions have demonstrated their potential as an imaging tool for nuclear structure by examining anisotropic flow and its correlations with the mean transverse momentum. Hints of a triaxial...
A number of new four-quark states containing from one to four $c$ or $\overline c$ quarks have been observed recently. Many of these new states have been discovered at the LHC. The production of these states via intrinsic charm in the proton is investigated. The tetraquark masses obtained in this approac agree well with the measured masses [1]. These calculations can provide some insight...
Approximately fifty years ago, the polarization of $\Lambda$ hyperons produced in unpolarized proton-beryllium collisions was discovered, though the origin of this phenomenon remains elusive. Many studies indicate that final-state effects, particularly from hadronization, play a significant role. Recently, it has been proposed that spin correlations of $\Lambda$ hyperons could provide insight...
The first measurement of the two-point energy correlator (EEC) in Pb-Pb collisions has revealed its sizeable modifications with respect to the p-p baseline. Nevertheless, challenges arise in comparing these measurements due to selection bias caused by energy loss, which leads to a shift in the Pb-Pb EEC spectrum toward smaller angles as compared to the p-p measurement. In this talk, we will...
The intriguing phenomena emerging in high-density quantum chromodynamics (QCD) matter are being extensively studied in the LHC’s heavy ion program, and will be explored in greater depth during the high-luminosity LHC (HL-LHC) era. To meet the challenges of HL-LHC, the CMS experiment is undergoing significant Phase-2 upgrades, including the MIP Timing Detector (MTD), which provides 30 ps timing...
The recombination production of $B_c$ mesons in heavy-ion collisions at the LHC energy is facilitated by the abundant and highly thermalized charm ($c$) quarks transported in the deconfined medium created. We study the production of $B_c$ mesons via $c$ and bottom ($b$) quark recombination in a statistical fashion by placing $B_c$ in the position of a member of the family of open $b$ hadrons,...
Measurements of top-quark pairs in heavy-ion collisions are expected to provide novel probes of nuclear parton distribution functions at high Bjoerken-$x$ values, which are difficult to access experimentally using other available probes. We report the observation of top-quark pair production in proton-lead collisions at the centre-of-mass energy of 8.16 TeV in the ATLAS experiment at the LHC....
Heavy quarks (charm and beauty) are useful probes for investigating the properties of the quark-gluon plasma (QGP) generated in ultra-relativistic heavy-ion collisions. Their participation in the collective motion of the medium can be assessed by measuring the charm-hadron elliptic-flow coefficient $v_2$, originating from the initial-state spatial asymmetry in non-central heavy-ion collisions....
Jet substructure is a powerful tool for testing QCD in elementary particle collisions. The two-point energy-energy correlator (EEC), defined as the energy-weighted cross section of particle pairs inside jets, is a novel jet substructure observable probing the correlation of energy flow within jets. In pp collisions, the angular dependence of the EEC cross section shows a distinct separation of...
We present a novel Monte-Carlo implementation of the EKRT model, MC-EKRT, for computing partonic initial states in high-energy nuclear collisions [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...
The interplay between the chiral anomaly and strong magnetic or vortical fields generated in off-central heavy-ion collisions is theorized to produce anomalous chiral effects in the quark–gluon plasma, such as the Chiral Magnetic Effect (CME) and the Chiral Vortical Effect (CVE). These effects have been actively studied by several experiments for over a decade as they could shed light on the...
A new fixed-target experiment, NA60+, is proposed at the CERN SPS to measure muon pairs in the centre-of-mass energy range from 6 to 17 GeV across various collision systems, from Pb--Pb to p--Be. Its physics scope spans topics from thermal radiation, to chiral symmetry restoration, strangeness, and charm production.
The experimental apparatus comprises a vertex spectrometer and a...
It has recently been widely acknowledged that the initial stages are important for correctly describing jet quenching in heavy-ion collisions. In particular, the initial stages influence the emission spectrum of hard partons traversing the plasma. Such calculations require the knowledge of the momentum-broadening kernel $C$, which describes the probability of a jet parton receiving a momentum...
In heavy-ion collisions, jets propagating through the quark-gluon plasma undergo interactions with the medium. These interactions modify the internal structure of jets, making jet substructure an invaluable tool for probing the microscopic properties of the QGP. N-point Energy Correlators, defined as energy-weighted N-particle correlations inside jets, have emerged as a novel substructure...
The FoCal is a high-granularity forward calorimeter to be installed as an ALICE upgrade during the LHC Long Shutdown 3 and take data in Run 4. It will cover a pseudorapidity interval of $3.2 < \eta < 5.8$, allowing to explore QCD at unprecedented low Bjorken-$x$ of down to $\approx 10^{-6}$ - a regime where non-linear QCD dynamics are expected to be sizable.
The FoCal consists of a compact...
High-energy partons are known to lose energy when passing through the hot and dense medium produced in heavy-ion collisions. This energy loss depends on the mass, flavor of the fragmenting parton and on the structure of the partonic shower, providing valuable insights into the properties of the QCD medium. This talk presents new results from the ATLAS Collaboration, exploring the flavor...
Due to their large mass, beauty quarks are always produced in hard-scattering processes, and hence their production can be computed with perturbative quantum chromodynamics (pQCD) calculations. The production cross section of beauty hadrons can be theoretically described with the factorisation approach as a convolution of the parton distribution functions of the incoming projectiles, the...
The $\Lambda$ polarization is a crucial probe of the gradients of velocity and temperature in the quark-gluon plasma generated in heavy-ion collisions. However, it is still not systematically used to tune hydrodynamic models. In this talk, we investigate the influence of different initial conditions and parametrization of the bulk viscosity on $\Lambda$ polarization, showing that they affect...
We include the perturbative JIMWLK energy evolution into the IP-Glasma initial state description used to simulate the early-time dynamics in heavy ion collisions. By numerically solving the JIMWLK equation on an event-by-event basis, we obtain the energy (Bjorken-$x$) dependent structure of the colliding nuclei. This enables us to predict how the initial state evolves when moving from RHIC to...
In heavy-ion collisions, hard-scattered partons lose energy as they traverse the medium, which is simultaneously modified by this interaction. One expected medium modification, known as the "diffusion wake," is a particle enhancement in the direction of the parton and a depletion in the opposite direction. Although theoretically predicted, clear experimental evidence of the diffusion wake...
A subset of heavy-ion collisions are ultra-peripheral collisions (UPC), where the ions collide with a large impact parameter, causing them to interact primarily through their intense electromagnetic fields. These interactions allow for the study of various photon-induced processes at high energies. The products of exclusive UPC interactions are typically characterized by very low transverse...
It is known from earlier studies that the hadronic interaction affects the measured yield of short lived resonance e.g. $K^{*0}$. Recent studies [1] show that the directed flow ($v_{1}$) of $K^{*0}$ is strongly affected during the hadronic stage due to asymmetric loss in different sides of the $p_{x}$ axis in momentum space caused by the tilted fireball and density dependent rescattering....
In an ultra-peripheral collision, where the impact parameter is larger than the sum of the nuclear radii, the nuclei mainly interact electromagnetically. These reactions are mediated by virtual photons. A photon can interact with a gluon in the target nucleus and produce a pair of charm quarks. These charm quarks then fragment and are observed as open charm hadrons ($\rm D^{0}$, $\rm D^{∗}...
The sPHENIX experiment is a next-generation collider detector at RHIC designed for rare jet and heavy flavor probes of the Quark-Gluon Plasma. The experiment includes large-acceptance, hermetic electromagnetic (EMCal) and hadronic (HCal) calorimeter systems, along with a very high-rate data acquisition plus trigger system. In RHIC Run-24, sPHENIX sampled 107/pb of p+p collision data at 200 GeV...
The diffusion wake accompanying the jet-induced Mach cone provides a unique probe of the properties of quark-gluon plasma in high-energy heavy-ion collisions. It can be characterized by a depletion of soft hadrons in the opposite direction of the propagating jet. We explore the 3D structure of the diffusion wake induced by γ-triggered jets in Pb+Pb collisions at the LHC energy within the...
Heavy quarks serve as a clean probe of the quark-gluon plasma (QGP) produced in high-energy nuclear collisions. They are primarily generated from early-stage hard scatterings and retain information about the entire evolution of the QGP fireball. We have developed a state-of-the-art model to provide a comprehensive description of the heavy quark evolution in a realistic QGP medium from the...
According to quantum chromodynamics, at high energy, hadrons exhibit a dynamic equilibrium between gluon splitting and recombination, known as saturation. Diffractive photonuclear production of J/ψ vector mesons provides unique insights into the gluon distribution of hadrons. The Mandelstam-t variable, representing the momentum transfer, probes hadron structure within the impact-parameter...
The observation of the vector meson's global spin alignment by the STAR Collaboration reveals that strong spin correlations may exist for quarks and antiquarks in relativistic heavy-ion collisions in the normal direction of the reaction plane. We propose a systematic method to describe such correlations in the quark matter. The correlations can be classified as local and long range types. We...
This talk presents recent ATLAS measurements investigating correlations between the 'ridge' - azimuthal correlations between particles in the underlying event that extend over all rapidities - and hard scattering processes in $pp$ and $p$+Pb collisions. To study this soft-hard correlation, measurements of two-particle correlations in with two different particle-pair selections are studied. In...
The first measurement of two-particle angular correlations for charged particles with LEP-II data is presented. The study is performed using archived hadronic $e^+e^-$ data collected by ALEPH at center-of-mass energies up to 209 GeV, above the $WW$ production threshold, which provide access to unprecedented charged-particle multiplicities and more complex color-string configurations if...
The fully stripped ions used in heavy ion collisions at the LHC are an excellent source of high-energy quasi-real photons. These can interact with photons emitted by the oncoming nucleus, or with the nucleus itself, either directly in inelastic processes or diffractively via pomeron exchange. Diffractive photonuclear processes can produce exclusive vector mesons that are uniquely sensitive...
In relativistic heavy-ion collisions, top quarks are expected to be attractive candidates for probing the quark-gluon plasma as well as to bring unique information about the time evolution of strongly interacting matter. We report the first study of top-quark pair production in lead-lead collisions at the centre-of-mass energy of 5.02 TeV with the ATLAS experiment at the LHC. The dataset was...
The appearance of vortical structures originating from gradients is a ubiquitous signature of collective fluid dynamic motion. We present event-by-event simulations for central asymmetric light+heavy and Au+Au collisions to investigate the formation and evolution of vortex-ring structures in the longitudinal flow velocity profile [1]. The production-plane polarization of $\Lambda$ hyperons,...
Although strong magnetic fields are expected in off-central heavy ion collisions, directly measuring their imprints, such as chiral magnetic effects, remains challenging. In this talk, we propose baryon electric charge correlation, $\chi^{\rm BQ}_{11}$, as well as the chemical potential ratio, $\mu_{\rm Q}/\mu_{\rm B}$, as useful probes for the detection of magnetic fields in heavy ion...
In ultra-relativistic heavy ion collisions, the charged ions produce an intense flux of equivalent photons. Photon-induced processes are the dominant interaction mechanism when the colliding nuclei have an impact parameter larger than the nuclear diameter. In these ultra-peripheral collisions (UPCs), the photon provides a clean, energetic probe of the partonic structure of the nucleus,...
Quarkonium production in high-energy hadronic collisions is sensitive to both perturbative and non-perturbative aspects of quantum chromodynamics (QCD) calculations. Charmonium cross section can be split into prompt and non-prompt components, the first corresponding to directly produced charm-anticharm pairs, the second originating from the decay of beauty hadrons. Both components are...
The observation of global and local spin polarization in heavy-ion collisions is explained as being induced by thermodynamics gradients of the QGP at local thermal equilibrium, such as the thermal vorticity and the thermal shear. However, since not all the features of the measurements can be well reproduced by the models, the assumption that the spin degrees of freedom of the QGP are...
Jet substructure provides precise tests of Quantum Chromodynamics (QCD) and offers more differential ways to study hadronization mechanisms, compared to measurements of single hadrons. QCD predicts that jet radiation patterns depend on the mass and color charge of the initiating parton. Parton showers, in particular, are sensitive to the different Casimir factors of quarks and gluons, as well...
Charm-baryon production measurements in proton-proton (pp) collisions at the LHC are fundamental to investigate the charm-quark hadronization, and to test perturbative QCD-based calculations. Recent measurements in pp collisions show baryon-to-meson ratios significantly higher than those in $\mathrm{e^+e^-}$ collisions, challenging the validity of theoretical calculations based on the...
We expect to probe the QCD phase diagram in the region beyond the critical point at the beam energy scan program at Relativistic Heavy-Ion Collider (RHIC) and at the upcoming Facility for Antiproton and Ion Research (FAIR). In this region, the heavy-ion collision systems will undergo a first-order phase transition. This phase transition is expected to proceed via spinodal decomposition as the...
Experimental information on the strong interaction between $\Sigma$ hyperons and protons is a crucial input for both the description of the equation of state of neutron stars with hyperon content and theoretical predictions regarding potential $\Sigma$-hypernuclei. Data on this interaction are scarce, solely based on scattering experiments. Since data points are only available at rather high...
Quarkonium production has long been identified as one of the golden probes to study the quark-gluon plasma (QGP). Among many observables, the measurement of azimuthal anisotropies in quarkonium production has a special role to shed light on the collective behavior of particles in a strongly interacting medium. In particular, the magnitude of the $\rm{J}/\psi$ elliptic flow measured at the LHC...
In heavy-ion collisions, the transverse momentum broadening coefficient, $\hat{q}$ plays an integral role in characterising how a high-energy parton loses energy to the quark-gluon plasma (QGP) through which it passes. Over the last few years, it has been shown [1,2] that $\hat{q}$ starts to receive radiative corrections at $\mathcal{O}(g^2)$, featuring potentially large logarithms. Indeed,...
The multistage approach based on hydrodynamics has achieved remarkably success in modeling heavy-ion physics, providing an accurate description of experimental particle spectra as well as various signatures of collective flow, flow correlations, and fluctuations. However, traditional numerical simulations of hydrodynamics are challenged by recent high-precision measurements: to probe the finer...
Characterizing the quark--gluon plasma (QGP) created in ultrarelativistic heavy-ion collisions requires identifying observables sensitive to different stages of the collision. Recent studies show that measuring collective anisotropic flow and the complex interplay between its Fourier harmonics ($v_n$) and $(\Psi_n$) can effectively disentangle contributions from various collision phases,...
Measurements at RHIC and the LHC show strongly enhanced baryon-to-meson yield ratios at intermediate transverse momenta ($p_{\rm{T}}$) in inclusive measurements from high-energy nuclear collisions compared to $p$+$p$ baseline. This enhancement is attributed to strong hydrodynamic flow and parton recombination in the Quark-Gluon Plasma (QGP).
Jet probes have been used extensively to gain...
In recent years, machine learning has emerged as a powerful computational tool and novel problem-solving perspective for physics, offering new avenues for studying strongly interacting QCD matter properties under extreme conditions. In this talk I will aim to provide an overview of the current state of this intersection of fields, focusing on the application of machine learning to theoretical...
The unexpected pattern of global spin alignment of vector mesons observed in relativistic heavy-ion collisions for different particle species have posed a strong challenge to theoretical interpretation, as it cannot be explained solely through conventional polarization sources such as vorticity and electromagnetic fields. We argue that fluctuations of strong-force fields with short correlation...
The observation of collective-like behaviors in pp and p–Pb collisions at LHC energies has sparked debate about the similarities between the dynamics of small systems and heavy-ion collisions. In this talk, our latest published results are presented, showing baryon-meson $v_{\rm 2}$ grouping (within 1$\sigma$) and significant splitting (approximately 5$\sigma$) at intermediate $p_{\rm T}$ in...
The NA61/SHINE strong interaction program is dedicated to exploring the phase diagram of strongly interacting matter. Its primary goals are to study the onset of deconfinement and to search for the critical point within this type of matter. To accomplish these objectives, the program conducts scans over a range of beam momenta (from 13A to 150A/158A GeV/c) and system sizes, involving...
Measurements of jet substructure observables in heavy-ion collisions provide powerful constraints on the microscopic mechanisms of interactions between energetic partons and the QGP. Though there has been remarkable progress in measuring inclusive charged-particle jet substructure observables, a complete understanding of the identified particle production inside jets (jet hadrochemistry) and...
The evolution of a relativistic heavy-ion collision is typically understood as a process that transmutes the initial geometry of the system into the final momentum distribution of observed hadrons, which can be described via a cumulant expansion of the initial distribution of energy density and is represented at leading order as the well-known eccentricity scaling of anisotropic flow. We...
We compute medium corrections to the energy-energy correlator (EEC) for jets in electron-nucleus collisions at leading order in the QCD coupling and the interaction of the jet with the medium. We derive an analytical expression for the modification of the EEC as a function of the opening angle and show that the modification is strongest at large angles within the jet cone. We obtain explicit...
We present the first set of fully-nonlinear, necessary and sufficient conditions guaranteeing causal evolution of the initial data for the Israel-Stewart equations with shear and bulk viscosity from kinetic theory coupled to a nonzero baryon current. These nonlinear constraints not only provide causality: they also (a) guarantee the existence of a locally well-posed evolution of the initial...
Relativistic heavy-ion collisions create a hot, dense state of QCD matter called Quark–Gluon Plasma (QGP). In ultra-central collisions, the QGP volume saturates and remains constant; instead, entropy fluctuations cause temperature variations in the system. This property can be probed by measuring the correlation between the average transverse momentum (⟨$p_{\rm T}$⟩) and the multiplicity of...
Event-by-event fluctuations of the transverse momentum per particle $[p_T]$ have been measured in heavy-ion collisions at RHIC and LHC, but this topic has so far received less attention than anisotropic flow. Yet the physical mechanism is identical for both phenomena: A long-range correlation in the initial stages, followed by collective expansion. While the origin of anisotropic flow is a...
Lattice QCD calculations predict that chiral symmetry is restored in a smooth crossover transition between a quark--gluon plasma and a hadron resonance gas (HRG) at vanishing net-baryon density, a condition realized in heavy-ion collisions at the LHC. In this regime, the net-baryon number cumulants computed using the HRG and lattice QCD partition functions are in good agreement up to third...
In the past years, different observables related to the spin polarization of hadrons such as $\Lambda$-Baryons have attracted much attention and continue to find new applications.
While some measurements (such as the global polarization) are straightforwardly reproduced by assuming the spins of the particles to be in equilibrium, the explanation of more differential observables (such as the...
Radial flow and anisotropic flow are key observables used to study the expansion dynamics of the quark-gluon plasma (QGP). While anisotropic flow has been extensively explored, the collective nature of radial flow has remained less understood. This talk presents the first measurement of transverse momentum ($p_{\mathrm{T}}$) dependence of radial flow fluctuations, $v_0(p_{\mathrm{T}})$, over...
Hydrodynamic attractors are a universal phenomenon of strongly interacting systems that describe the hydrodynamic-like evolution far from local equilibrium. The rapid hydrodynamization of the Quark-Gluon Plasma is behind the remarkable success of hydrodynamic models of high-energy nuclear collisions. Until now, hydrodynamic attractors have been studied only in monotonically expanding systems,...
Measurements of dijet production in heavy ion collisions can be used to probe the nuclear matter. In proton-lead collisions, the normalized average dijet pseudorapidity distributions can be used as a sensitive tool for constraining the nuclear modifications of parton distribution functions (nPDF) at different $Q^2$ scales and Bjorken-$x$. In such studies, it is possible to investigate, with a...
Finite density lattice QCD usually relies on extrapolations in baryon
chemical potential ($\mu_B$), be it Taylor expansion, T' expansion or
analytical continuation. However, their range of validity is difficult to
control. In the canonical formulation, the baryon density is the
parameter of the system, not $\mu_B$.
Here we demonstrate that we can access finite density QCD in the...
Xenon (Xe) nuclei are deformed and have a non-zero quadrupole moment, whereas lead (Pb) nuclei are considered spherical in shape. The study of Xe-Xe collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{_{\mathrm{NN}}}} = 5.44$ TeV opens up a window to study nuclear deformation at LHC. When compared to Pb-Pb collisions at $\sqrt{s_{_{\mathrm{NN}}}} = 5.36$ TeV, one can explore...
In this report, we present measurements of $^3_\Lambda H$ and $^4_\Lambda H$ in Ag+Ag collisions at $\sqrt{s_{NN}}$ = 2.55 GeV, conducted with the HADES experiment at GSI. While at RHIC and LHC energies hypernuclei production is typically discussed with a focus on two scenarios, statistical production in full equilibrium versus production via coalescence, at SIS energies, the spatial region of...
Understanding strangeness enhancement in proton-proton (pp) collisions at the LHC remains a challenge for hadronization models. Recent observations of the $\Omega_\mathrm{c}^0$ baryon indicate that a substantial fraction of the detected Ω baryons may originate from the decay of charm hadrons, e.g. from $\Omega_\mathrm{c}^0 \rightarrow \Omega^- + \pi^+$. However, the unknown absolute branching...
We generalize the relativistic magnetohydrodynamic (MHD) theory recently derived in Ref. [1] to describe the dissipative dynamics occurring in accretion disks in presence of large magnetic fields. For this purpose we consider a relativistic dilute gas composed of electrons and ions described by the Boltzmann-Vlasov equation and simplify it using the 14-moment approximation. This procedure...
The shape and orientation of colliding nuclei play a crucial role in determining the initial conditions of the QGP formed in central collisions, which influence key observables such as anisotropic and radial flow. For instance, central collisions of near-spherical Au nuclei create a QGP with a fixed, circular geometry, whereas prolate-shaped uranium nuclei can collide in a variety of...
Studies of strong interactions between hadrons provide a valuable opportunity to test Quantum Chromodynamics at nucleon-scale distances. The femtoscopy technique has proven to be an effective tool for studying interactions between unstable hadrons by measuring the correlation function of hadron pairs in momentum space. This approach offers insights into the interaction between two hadrons,...
The six-hour Xe-129 run at the LHC has produced a remarkable wealth of physics, among which several studies of its nuclear shape. Previous works indicate that the elliptic flow ratio with Pb-208 collisions determines the quadrupole deformation ($\beta_2$) of Xe, while the $\rho_2$ elliptic flow-mean $p_T$ correlator informs us about the so-called triaxiality ($\gamma$). In this work, we go one...
We demonstrate that astrophysical constraints on the dense-matter equation of state place an upper bound on the color-superconducting gap in dense matter above the transition from nuclear matter to quark matter. Pairing effects in the color-flavor locked (CFL) quark matter phase increase the pressure at high density, and if this effect is sufficiently large then the requirements of causality...
One of the unresolved issues in hadron–hadron collisions is the microscopic understanding of how light (anti)(hyper)nuclei are created. Several differential measurements of (anti)(hyper)nuclei yields, momentum distributions, and fluctuations have been carried out in pp, p–A, and A–A collisions at ultra-relativistic energies. Comparisons to models based on statistical hadronization or nucleon...
We develop a comprehensive analytic framework for jet quenching in QCD media, based on a medium-induced parton cascade sourced by collinear virtual splittings. We show that the energy flow out of the jet cone, driven by turbulent gluon cascades, is governed by a non-linear rate equation that resums gluon splittings at arbitrary angles and is enhanced by the medium length, L. The solution of...
The observation of long-range correlations is a crucial indicator of collectivity in heavy-ion collisions and has been instrumental in establishing the formation of quark-gluon plasma (QGP) at RHIC and LHC. In this study, the first direct measurement of radial flow is presented using a new observable, $ v_{\rm 0}(p_{\rm T}) $, formulated to capture the long-range correlations in the transverse...
Strangeness production in high-energy hadronic and nuclear collisions continues to be one of the central topics in the study of strongly interacting matter. The data collected by the NA61/SHINE experiment at the CERN SPS North Area allows for a comprehensive scan of the strangeness production across various collision energies and system sizes.
This presentation will focus on the new...
The effective kinetic theory of QCD provides a possible picture of various non-equilibrium processes in heavy- and light-ion collisions. While there have been substantial advances in simulating the EKT in simple systems with enhanced symmetry, eventually, event-by-event simulations will be required to test this physical picture. As of now, these simulations are prohibitively expensive due to...
The semi-inclusive deep inelastic scattering (SIDIS) and Drell-Yan (DY) processes are primary channels for studying the parton distributions of the proton and the nucleus, and for deducing the properties of cold nuclear matter. However, for nuclear targets, the DY and SIDIS differential cross-sections are modified by multiple interactions between the active parton and spectator nucleons, which...
Intermediate to low energy heavy-ion collisions are sensitive to the finite temperature ($T$), high baryon number density ($n_B$) QCD equation of state (EoS) at a ratio between charged and total number of baryons that is fixed by the colliding species. For typical nuclei used in collisions, like gold and lead, this ratio, also known as the charge fraction ($Y^{\rm QCD}_Q$), is around 0.4. On...
We study the effect of magnetic field on particle ratios and charge fluctuations in hadron resonance gas. We argue that the big change in the pion to proton ratio is due to ill-defined description of higher-spin states, and that because of detailed balance, neutral resonances must be affected by the field too. The calculated fluctuations of conserved charges are likewise suspicious and must be...
The study of exotic hadrons has long been a topic of great interest for the understanding of Quantum Chromodynamics (QCD). As one of the light exotic hadrons, the structure and constituent quark content of $f_0(980)$ have been debated for decades, with theories suggesting it could be a tetraquark state ($s\bar sq\bar q$) or a hadronic molecule ($K\bar K$). Recently, the CMS experiment has...
The D-measure of the event-by-event net charge fluctuations was introduced over 20 years ago as a potential signal of quark-gluon plasma (QGP) in heavy-ion collisions, based on the fractional charges of quarks leading to suppression of fluctuations relative to hadron gas baseline. Measurements have been performed at RHIC and LHC, but in the absence of quantitative calculations for both...
The event-by-event shapes of colliding nuclei are imprinted on flow patterns measured in relativistic heavy-ion collisions because of the strong hydrodynamic response to collision geometry. In this work, we perform high-statistics simulations to study the impacts of nuclear structure on the ratios of anisotropic flow observables between different collision systems. We study...
Production of nuclei and hypernuclei in relativistic ion collisions.
A. Botvina and M. Bleicher.
Institute for Theoretical Physics, J. W. Goethe University,
D-60438 Frankfurt am Main, Germany.
We investigate the formation of light nuclei and hypernuclei in the
rapidly expanding nuclear matter after relativistic nucleus-nucleus
collisions. The primary hadronization phase...
With its precise vertex reconstruction and particle identification capabilities, the LHCb detector is ideally suited to study the production and polarization of strange particles. In addition, being the origin of hyperon polarization from unpolarized proton-proton and proton-nucleus collisions not yet fully understood, measurements in different collision systems and kinematic ranges must be...
The chiral phase transition in (2+1)-flavor QCD is expected to be of second order if the breaking of axial anomaly remains sufficiently strong at the chiral phase transition temperature $T_c$ [1]. This is supported by lattice QCD calculations [2]. However, FRG model calculations suggest that the scaling window, in which universal scaling relations hold, may be small [3]. Furthermore, whether...
The strong interaction in the non-perturbative regime typical of the system created in Heavy-Ion collision has been studied in the past years through an effective Quasi-Particle Model ($QPM$): we present an extension to a more realistic model, named $QPMp$, incorporating momentum-dependent parton masses as entailed by QCD asymptotic free dynamics. This model naturally improves the description...
Introduction of a nonzero isospin chemical potential in QCD leads to the emergence of a pion condensed phase at sufficiently large $\mu_I$, bounded by a second order transition line. At zero temperature the pion condensate appears at $\mu_I = m_\pi/2$. Recent numerical studies at physical quark masses show that the pion condensation boundary remains vertical up to the meeting point with the...
Fluctuations and correlations of conserved charges serve as sensitive observables for investigating QCD thermodynamics. In particular, baryon-strangeness correlations may offer insights on changing degrees of freedom carrying strangeness.
In this work, we present the measurements of baryon-strangeness correlations in Au+Au collisions from the beam energy scan program (BESI and BESII,...
The open quantum system framework allows one to compute quarkonium's evolution in a medium, keeping track of the needed quantum features. However, computing this evolution is a computationally demanding task. QTRAJ is an efficient code that allows one to simulate the behavior of quarkonium in a medium in the case in which the medium sees quarkonium as a small color dipole $rT\ll 1$. While this...
The elliptic anisotropy of energetic particles produced in heavy-ion collisions is understood as an effect of a geometrical selection bias due to energy loss. In the measured ensemble, particles oriented in the direction in which the medium is shorter are over-represented as compared to those oriented in the direction in which the medium is longer. In this work we present the first...
The measurement of dielectron production is a fundamental piece of the puzzle in the understanding of the hot and dense matter produced in ultra-relativistic heavy-ion collisions. The dielectron spectrum provides information that penetrates the veil of final-state hadronic interactions and provides direct access to the early phases of the collision. However, the interpretation of the measured...
The production of a Z boson provides a clean handle to control the population of events to be studied. By selecting muonic decays of Z bosons, we can isolate the effect of the recoiling process without potential bias from requiring isolation, as is the case for photons. Di-hadron correlations can naturally separate effects from different angular scales and enable jet substructure measurements...
Open charm production is a sensitive probe of both hot and cold nuclear matter effects. Charm meson production provides strong constraints on nuclear parton distributions, while charm baryon and strange charm hadron production can be used to probe strangeness- and baryon-enhancing hot QCD effects, respectively. The LHCb detector is designed to study heavy flavor hadrons at the LHC, providing...
Strangeness production has been suggested as a sensitive probe to the early dynamics of the deconfined matter created in heavy-ion collisions.
There are significant discussions in the field about the initial conditions, including the colliding energy and the size of the system, needed to generate a quark-gluon plasma (QGP). It is expected that the threshold can be revealed by the measurements...
Modifications of quarkonia production in hadronic collisions provide an important experimental observable to probe the heavy quark interaction with the nuclear medium. The excited ψ(2S) state, with a relatively low binding energy, is especially sensitive to these effects. In thiscontribution, we will present a new LHCb result on ψ(2s)/J/ψ production in PbPb collisions, along with progress on...
The first measurement of low transverse momentum ($p_\mathrm{T}$) charged hadron pseudorapidity and azimuthal angle distributions relative to $Z$ bosons in PbPb collisions at nucleon-nucleon center-of-mass energy $\sqrt{s_\mathrm{NN}} = 5.02$ TeV is presented. This study utilizes PbPb collision data recorded in 2018 with an integrated luminosity of $1.67 \pm 0.03$ nb$^{-1}$, as well as pp...
We present a newly developed hybrid hadronic transport + hydrodynamics geared towards heavy ion collisions (HICs) at low to intermediate beam energies, and report on the resulting excitation function of dileptons. In this range of energies, covered by the STAR Beam Energy Scan program and the future CBM experiment at FAIR, it is unclear how to best decribe the medium evolution. At which beam...
Hypernuclei are bound states of nucleons and hyperons. The measurement of the production of hypernuclei with mass number A=3 and 4 in heavy-ion collisions is a powerful tool to investigate the hyper-nucleosynthesis mechanism. In the coalescence model, the production yields are sensitive to the interplay between the spatial extension of the nucleus wavefunction and the baryon-emitting source...
Understanding the properties of hypernuclei is crucial for constraining the nature of hyperon-nucleon ($Y\text{-}N$) interactions, which plays a key role in determining the inner structure of compact stars. The lightest (anti-)hypernuclei are the hypertriton ($^3_\Lambda\text{H}$), which consists of a pair of nucleons and a $\Lambda$ hyperon, and its anti-nucleus...
A search for medium-induced jet transverse momentum broadening is performed with isolated photon-tagged jet events in pp and PbPbcollisions at n5.02 TeV. The difference between jet axes as determined via energy-weight and winner-take-all clustering schemes, also known as the decorrelation of jet axes and denoted Δj, is measured for the first time in photon-tagged jet events. This observable is...
Charmonium production has long been identified as one of the golden probes to study the quark–gluon plasma (QGP). In fact, the early production of heavy quarks ($c\bar{c}$ and $b\bar{b}$) make charmonia an ideal tool to investigate the evolution of the hot and dense medium produced in ultra-relativistic heavy-ion collisions. Moreover, at LHC energies the recombination of uncorrelated charm...
Transport coefficients play an important role in characterizing hot and dense nuclear matter, such as that created in ultra-relativistic heavy-ion collisions (URHIC). The electric conductivity can be accessed via the electromagnetic (EM) spectral function's low-energy transport peak, which can be measured via thermal dilepton emission. Several facilities including the Schwer-Ionen Synchrotron...
In this talk, we present the first measurement of $\mathrm{D}^0$ photoproduction in heavy ion ultraperipheral collisions (UPCs) using the data collected by CMS experiment during 2023 PbPb collisions at LHC. The measured production cross sections are presented as a function of the $\mathrm{D}^0$ transverse momentum (2$< p_{T} <$12 GeV/c) and rapidity (-2< y <2). Additionally, we will present...
Electromagnetic probes are a unique tool for studying the space-time evolution of the hot and dense matter created in ultra-relativistic heavy-ion collisions. Photons and dielectron pairs are emitted during the entire evolution of the medium created in such collisions, providing access to direct-photon production that includes thermal radiation from the early hot stages of the collision. The...
Fluctuations of conserved charges in heavy-ion collisions are expected to be sensitive to a critical point in the phase diagram of QCD matter [1, 2]. Such a critical point is increasingly predicted to be located in the high baryon chemical potential ($\mu_B$) region around $\mu_B$ = 500 - 650 MeV [3–8]. In 2018, the STAR Experiment started collecting data in a fixed-target configuration in...
This presentation discusses recent results on femtoscopic correlations involving $D^0$ ($\bar{D0}$) mesons and hyperon polarization in pPb collisions at $\sqrt{s_{NN}}=8.16$ TeV. The femtoscopic measurements investigate the strong interaction for pair combinations of particles, allowing to extract the scattering observables accessible through their correlation functions. The results may...
We present a selection of recent measurements of electromagnetic probes conducted by CMS to probe initial-state aspects of the heavy ion collision. The Z boson has a very short lifetime and can decay to dimuon final states that can be precisely measured. These properties make it a valuable tool for studying the initial state of heavy ion collisions. It has been proposed that the momentum of...
The study of $\rm{J}/\psi$ photoproduction in ultraperipheral collisions (UPCs) offers a powerful probe of gluon dynamics in heavy nuclei. In UPCs, photons can interact with the nucleus coherently (involving the entire nucleus) or incoherently (with individual constituents). While coherent processes provide insight into the average gluon density, incoherent photoproduction is uniquely...
Anisotropic flow characterizes the shape and direction of expansion of the medium created in heavy-ion collisions. The Fourier coefficients in the expansion of particle azimuthal distribution describe the collective response of the medium to the shape of the initial collision geometry,
and are sensitive to the equation of state (EOS). A non-monotonic slope in the first-order flow coefficient...
Measurements of identical pion femtoscopy offer insights into collision dynamics, such as collective expansion, geometry of the collision zone at freeze-out, etc. In addition to the quantum interference among the pion pairs, Coulomb interactions between the pair and the net positive charge in the emitting source affect the final measurements as well. Furthermore, due to the imbalance of...
We contrast the behavior of ordinary and factorial cumulants of proton number and point out that the latter has numerous advantages over the former, in particular with regards to the critical point search in heavy-ion collisions. The new RHIC BES-II data on factorial cumulants of protons is analyzed, indicating clear deviation of two- and three-particle proton correlations from the...
Particle correlations are powerful tools for studying quantum chromodynamics in hadron collisions. In heavy-ion collisions, azimuthal angular correlations probe collective phenomena in hot, dense, nuclear media, such as QGP. In small collision systems, they could point to final-state effects or potential initial-state correlations. The LHCb experiment has the unique ability to study particle...
Heavy-ion collisions offer a new way to understand hyperon-nucleon ($Y$-$N$) interactions. The two-particle correlation in pair relative momentum, which reveals valuable information about the space-time evolution of the particle-emitting source and final state interactions involving hyperons, is the primary observable of interest. The measurements of correlations between light nuclei ($d$,...
In relativistic heavy-ion collisions, $J/\psi$ photoproduction serves as a sensitive probe for studying the gluonic structure in heavy nuclei. Differential measurements of photon-induced $J/\psi$ production provide important constraints on gluon distribution functions and sub-nucleonic shape fluctuations. The linear polarization of photons involved in these processes enables imaging of the...
Relativistic heavy-ion collisions at the RHIC Beam Energy Scan program and SPS energies probe the QCD phase diagram at finite baryon densities. Precise photon and dilepton measurements serve as unique tomographic probes for the properties of hot nuclear matter. In this work, we study the electromagnetic radiation from relativistic heavy-ion collisions from 7.7 to 200 GeV. The dynamical...
Heavy quarks (i.e. charm and beauty) are powerful tools to characterize the quark-gluon plasma (QGP) produced in heavy-ion collisions. Although they are initially produced out of kinetic equilibrium via hard partonic scattering processes, recent measurements of the anisotropic flow of charmed hadrons pose the question regarding the possible thermalization of heavy quarks in the medium. By...
Measurements of quarkonia production in peripheral and ultraperipheral
heavy-ion collisions are sensitive to photon-photon and photon-nucleus interactions, the partonic structure of nuclei, and to the mechanisms of vector-meson production. LHCb has studied production of the J/ψ and ψ(2s) charmonium states in peripheral and ultra-peripheral collisions using PbPb data at forward rapidity,...
We study the influence of the QCD critical point on the trajectories describing the evolution of the expanding fireball in heavy-ion collisions. We find that the lines of constant specific entropy (entropy per baryon) on the phase diagram are drawn towards a special point on the coexistence (first-order) line where the specific entropy reaches a maximum [1]. We study the interplay between this...
The three-dimensional structure of the initial state in heavy-ion collisions have become important topic of interest in the community, since it provides insights into the origins of anisotropic flow, the breaking of boost invariance, longitudinal de-correlation, and particle correlations observed after kinetic freeze-out. One of the important properties of the 3D initial state is the tilt of...
We propose the angular distribution of lepton pairs produced in ultrarelativistic heavy-ion collisions as a probe of thermalization of the quark-gluon plasma. We focus on dileptons with invariant masses large enough that they are produced through quark-antiquark annihilation in the early stages of the collision. The angular distribution of the lepton in the rest frame of the pair then reflects...
Non-monotonic behavior in the RHIC net proton number fluctuation data could signal the presence of a QCD critical point if they probe thermal conditions at the time of freeze-out. However, the connection between higher-order baryon number cumulants calculated in equilibrium QCD thermodynamics and higher-order net proton number cumulants may not be straightforward. Moreover, correlations...
Diffractive vector meson production is a golden channel in the search for gluon saturation. The color glass condensate (CGC) framework has been successfully applied to describe diffractive vector meson production in $e+p$ collisions at HERA. Predictions for $\gamma+Pb$ collisions realized in ultraperipheral collisions at the LHC are however overestimating the experimental data at large center...
We find a remarkable universality in the experimentally observed transverse momentum spectra in ultrarelativistic nuclear collisions, obtained by removing the global scales of total particle number and mean transverse momentum. This scaling behavior breaks down at large transverse momentum and for very small systems, such as those produced in p-p collisions. We further demonstrate that this...
Energy correlators inside of high energy jets provide a powerful tool to image the intrinsic and emergent angular scales of QCD. They have the potential to provide unprecedented insight on the interplay between vacuum scales inside of a jet and its medium modification. Energy correlators of jets containing a gluon splitting to heavy quarks can provide unique experimental access to two- and...
A recent suggestion for finding the QCD critical endpoint [arXiv:2410.16206]
is to investigate entropy contours on the QCD phase diagram. We generalize this
idea to other lines of constant observables, like that of strangeness
susceptibility. Such quantities can not be directly calculated in lattice QCD
because of the infamous sign problem. We present an analytical continuation of
various...
Recent CMS data revealed intriguing long-range correlations within high-multiplicity jets produced in proton-proton collisions, suggesting the potential onset of collective behavior, typically associated with heavy-ion collisions, at much smaller scales. Two-particle correlations in the “jet frame” show a surprising rise in elliptic flow harmonics, v2, at large pseudorapidity separations (Δη...
sPHENIX is a next-generation experiment at RHIC for jet and heavy-flavor physics which was fully commissioned during 2023 and 2024. Using its novel streaming-readout-capable, precision tracking system, sPHENIX collected 100 billion unbiased p+p collisions, and a further sample of minimum-bias Au-Au collisions, in Run-24. A key measurement of the sPHENIX heavy flavor physics program is the...
One of the most striking modifications induced by the QGP on a QCD parton shower is the breaking of angular-ordering. This was established in a series of pioneering papers almost 15 years ago by studying the radiation pattern off a QCD antenna in the presence of a medium [1,2]. These effects were captured by a single critical angle solely depending on the medium properties. Constraining the...
The charm quark is formed almost exclusively during the initial stages of the collision, and a significant fraction of the charm quarks fragment into the $D^{0}$ meson, the lightest open-charm hadron. We can gain insights into the interactions between the charm quark and the quark-gluon plasma (QGP) medium by studying the production and the flow of $D^{0}$ meson in heavy-ion collisions. We...
Spin hydrodynamics is the extension of standard relativistic hydrodynamics with the total angular momentum considered as an independent conserved charge, where the total angular momentum is often expressed as a surface integral of a rank-3 tensor.
This rank-3 tensor is then decomposed into orbital and spin parts, which, by using the definition of orbital angular momentum in Cartesian...
In the past year, results for the location of the critical point from different
approaches seem to converge towards previous predictions from functional QCD.
We summarise recent theoretical results of the latter approach on the
Columbia plot [1], the QCD phase diagram and the location of the critical
point at finite baryon chemical potential [3]. We highlight our efforts to...
Measurements at the LHC have provided evidence for collective behavior in high-multiplicity pp and pPb collisions through multiparticle correlation techniques. However, no conclusive evidence of jet quenching—characterized by the energy loss of high-$p_\mathrm{T}$ partons traversing the medium—have been observed in these smaller systems. This paradox raises an intriguing question: How can a...
We compute the pressure, chiral condensate and strange quark number susceptibility from first principles within perturbative QCD at finite temperature and very high magnetic fields up to two-loop and physical quark masses. We also discuss cold and dense quark matter in the presence of a very strong magnetic field using perturbative QCD at finite density. The effectively negligible contribution...
Charm quarks serve as a sensitive probe of the Quark Gluon Plasma providing direct insights into its formation, evolution, and properties. We present the first-ever measurement of the elliptic flow of charm baryons, specifically prompt $\Lambda_c^+$, in lead-lead (PbPb) collisions at a center-of-mass energy of 5.36 TeV, using the CMS experiment. We also present the elliptic and triangular flow...
One method to estimate the position of the critical endpoint of QCD is to model the free energy as a rational function of the baryon chemical potential $\mu_B$ and determine the Lee-Yang edge singularities. Using high-statistics simulations on 4HEX improved staggered $16^3\times 8$ lattices by the Wuppertal-Budapest Collaboration we estimate the location of the closest singularity in the QCD...
sPHENIX is a next-generation collider detector at RHIC which was successfully commissioned in 2023 and 2024 and took physics data in p+p and Au+Au collisions. In addition to its high-p$_T$ jet and heavy flavor physics program, sPHENIX is a general purpose collider detector with excellent capabilities for exploring collective phenomena in small and large systems. This is due to its large...
Over the past several years, significant progress has been made in leveraging rapidity-dependent measurements from colliders to gain insight about the early and late-time dynamics of relativistic nuclear collisions. In this study, we perform a systematic model-to-data comparison using simulations of Au-Au and $d$-Au collisions and a broad range of measurements from the PHENIX, STAR, PHOBOS,...
Charm quarks offer valuable insights into the properties and evolution of the QCD medium as they are generated in the initial moments of energetic heavy-ion collisions at Relativistic Heavy-Ion collider (RHIC) and Large Hadron Collider (LHC). In particular, they can carry signals from the pre-equilibrium stage since the very high energy density of this stage can result in significant...
Ultrarelativistic nuclear collisions have revealed the existence of a hot, dense medium exhibiting collective flow with minimal viscous dissipation, indicative of a strongly interacting quark-gluon plasma. The CMS Collaboration previously measured the speed of sound in this medium, determining a value of approximately 0.241 at an effective temperature of 219 MeV in ultracentral 5.02 TeV PbPb...
Understanding the applicability of fluid-dynamical models to describe the hot and dense matter produced in the early stages of hadronic collisions is a fundamental problem in the field. In particular, it is not clear to what degree this hydrodynamization process requires proximity to a local equilibrium state. In this contribution, we study this problem in kinetic theory considering an...
Heavy ion collisions provide a unique opportunity to access the space-time ordering of parton branching processes, since parton showers interact with a spatially-extended dense medium. However, the challenges of robustly isolating the formation time of a splitting phenomenologically has prevented formation time-dependent modification effects from being accessed experimentally. We address these...
Energy-energy correlators can isolate physics of different angular scales, which has attracted a lot of interest recently to study it in heavy ion environments. Any modification from proton-proton reference can reveal hints about the inner workings of the quark-gluon plasma. In this presentation, we will present the first measurement of the energy-energy correlator of jets in heavy ion...
We present a Bayesian analysis of equation of state (EOS) constraints using recent observational data for masses, radii and tidal deformability of pulsars and a class of hybrid neutron star EOS with color superconducting quark matter on the basis of a recently developed nonlocal chiral quark model.
The nuclear matter phase is described within a relativistic density functional model of the...
Results are shown from a one-dimensional femtoscopic analysis of $\text{K}^{0}_{\text{S}}\text{K}^{0}_{\text{S}}$ from Pb–Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. The centrality and transverse momentum in the pair reference frame $k_{\rm T}$ dependence is analyzed. These results are compared to previous results from ALICE at 2.76 TeV (J. Adams et al., 2015, Physical Review C 92,...
Resonances can give us multiple ways to probe the properties of the QCD matter created in nucleus-nucleus collisions at different time scales. Due to a short lifetime of about $4 fm/c$, $K^{*0}$ will primarily decay inside the fireball formed after the collision. Their decay daughters may undergo various in-medium effects, such as rescattering and regeneration. The resonance to non-resonance...
Light nuclei, such as deuteron and triton, are loosely bound object and their yields are expected to be sensitive to the baryon density fluctuations and may be used to probe the signature of 1st order phase transition and/or critical point in heavy-ion collisions. In the beam energy scan program at RHIC, the STAR experiment has taken the data of Au+Au collision at center of mass energy...
The puzzling phenomenon of collectivity in small systems has not been thoroughly explored, and many aspects still require investigation. Given the limitations of applying hydrodynamics to small systems, it is essential to develop alternative collective models that allow for better control over the degree of collectivity. In this poster, we present our latest advancements in solving a 2+1...
The quark-gluon plasmas produced in non-central relativistic heavy-ion collisions can have large vorticities, leading to spin polarization in a manner analogous to the Barnett effect. Such spin polarization has been observed in $\Lambda$ hyperons [1], spurring rapid development in the area of spin physics in heavy-ion collisions. However, tension remains between experimental data and theories...
Although calculations of QCD thermodynamics from first-principle lattice simulations are limited to zero net-density due to the fermion sign problem, it is possible to extend the equation of state (EoS) to finite values of the $B$, $Q$, $S$ chemical potentials via expansions around zero chemical potentials. Taylor expansion around $μ_i = 0$ with $i = B, Q, S$ enables to cover with confidence...
Despite abundant experimental evidence and numerical hydrodynamic simulations, transport of energy-momentum and charge in anisotropic plasma states, which are produced in off-central collisions, has not been adequately addressed from a theoretical point of view. In Ref. [1], a novel method was introduced, using holography to compute transport coefficients in strongly interacting plasma states...
The location of critical-point as per quantum chromodynamics (QCD) and the nature of phase transition is the subject of both theoretical and experimental studies. It is observed that local density fluctuations are directly related to the critical behaviour in QCD. As the system approaches phase transition, there is a divergence of the correlation length. The system becomes scale-invariant with...
The simultaneous description of jet observables such as the nuclear modification factor $R_{\rm AA}$ and elliptic flow $v_2$ as a function of transverse momentum is a challenge both in large and small colliding systems. For large systems there is the complication of the hydrodynamic background and response, whereas in small systems so far no measurable jet quenching could be identified. This...
Measurements of Balance Functions were proposed more than two decades ago to probe the evolution of particle production in relativistic heavy ion collisions by Pratt et al.. It subsequently emerged that Balance Functions can also be used to probe the susceptibility of QCD matter near the phase transition and the light quark diffusivity. I will briefly review the theoretical work done in the...
The ALICE Collaboration observed that the production of light-flavoured hadrons relative to pions increases with the charged-particle multiplicity evolving smoothly across interaction systems and energies, from pp collisions to nucleus-nucleus collisions. Notably, this observation extends to the strange hadron sector, where an enhanced production in heavy-ion collisions with respect to minimum...
When the Quark Gluon Plasma (QGP) forms during high-energy collisions, the dimensions of the produced droplet are dependent on the overlap region of the colliding nuclei, enabling the QGP to encode information about the initial conditions of nuclear collisions and even the structure of the colliding nuclei. The system of particles produced in the final state exhibit collective behavior, and...
Recent advances in quantum technologies and computation have conduced to novel theoretical developments, which have found applications in various research fields, including high-energy physics. This work presents an open quantum systems approach for studying the suppression of quarkonia [1], which has been considered for many decades a crucial probe for unraveling the main features of hot and...
This study reports measurements of event-by-event fluctuations in mean transverse momentum ($\langle p_{\rm T} \rangle$) using the integral correlator $\langle \Delta p_{\rm T} \Delta p_{\rm T}\rangle$ and the skewness of the event-wise $\langle p_{\rm T} \rangle$ distribution in pp collisions at $\sqrt{s}=13$ TeV. These measurements are conducted with the Monte Carlo event generators PYTHIA8...
In recent years, CMOS silicon pixel detectors have seen significant advancements and widespread usage across various physics fields, allowing for significant improvements in particle detection technologies. One relevant example is the ALPIDE chip, which is a CMOS Monolithic Active Pixel Sensor developed for the upgrade of the Inner Tracking System of the ALICE experiment at the LHC.
On top of...
RHIC data taken over two decades showed that even charm quarks thermalize in the hot system formed in Au+Au collisions at $\sqrt{s_{NN}}=$ 200 GeV. These measurements were constrained to the mid-rapidity region, where charm production peaks. The question is what is the longitudinal extension of the charm thermalization and how that would impact the quantification of charm diffusion in the...
The analysis of azimuthal-correlation distribution between $\rm{D^{0}}$ mesons and charged particles is very important for studying charm-quark production, occuring in the early stages of high-energy collisions via hard scattering. Following their production, charm quarks undergo a fragmentation process which results in a spray of charged hadrons after hadronization, typically collinear to the...
The azimuthal correlations of $\text{D}_{\text{s}}^{+}$ mesons with charged particles in high-energy proton-proton (pp) collisions offer a powerful tool for investigating charm-quark production and hadronization mechanisms. By measuring the azimuthal-angle distribution between the direction of the tagged $\text{D}_{\text{s}}^{+}$ meson and those of the other charm hadronization products, it is...
The production of beauty quarks can be calculated within perturbative Quantum Chromodynamics (pQCD) due to their large mass, allowing for precise comparisons with experimental results. Beauty-quark tagged jets (b-jets) allow to experimentally reconstruct the kinematics of the scattered beauty quark and probe its subsequent shower evolution.
Nonetheless, traditional b-jet tagging algorithms...
In high energy nuclear collisions, the majority of the charm and beauty quark production occurs via perturbative hard scattering on a short timescales and undergoes transport through a medium (which depends on the system), experiencing drag, diffusion, scattering, or recombination into bound states. Investigating these processes requires methods sensitive to both the production cross section...
Light nuclei production is expected to be sensitive to a QCD phase transition at large net-baryon densities which are accessible in heavy-ion collisions. I will present results of a study with the UrQMD transport model supplied with a density dependent equation of state including a first-order phase transition. These results include the time evolution of the cumulants up to third order of the...
A recently formulated extension of perfect spin hydrodynamics, which includes second-order corrections in the spin polarization tensor to the energy-momentum tensor and baryon current, is studied in the case of a one-dimensional boost-invariant expansion. The presence of second-order corrections introduces feedback from spin dynamics on the hydrodynamic background, constraining possible spin...
Quarkonium production in high-energy hadronic collisions is sensitive to both perturbative and non-perturbative aspects of quantum chromodynamics (QCD) calculations. From a theoretical point of view, 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 the available theoretical...
We calculate the suppression of the $\Upsilon$(nS) states in $p+{\rm Pb}$
collisions relative to $p+p$ collisions, including both cold matter effects (nuclear parton distribution function (nPDF) modifications, coherent energy loss, momentum broadening) and hot matter effects.
The suppression of bottomonium states in the hot medium is treated two ways: a next-to-leading-order open quantum...
Understanding the temperature dependence of the viscosity-to-entropy ratio (η/s) is essential for characterizing the properties of the matter produced in ultra-relativistic heavy ion collisions at RHIC and LHC. Low-p⊥ theory and data are, however, weakly sensitive to the commonly assumed forms of the temperature dependence of η/s, especially at high temperatures. To address this, we use...
Ultraperipheral collisions of relativistic heavy ion beams lead to a diverse set of photon-nucleus (photonuclear) interactions. Measurements of particles produced in photonuclear reactions can shed light on the QCD dynamics of these novel, extremely asymmetric colliding systems, with energies between those available at RHIC and the LHC. Previous studies by ATLAS have characterized photonuclear...
Energy-energy correlators (EECs), which are energy-weighted cross-sections of particle pairs, offer incisive probes into QCD dynamics, across the full scale of jet evolution, by separating energy scales in the jet fragmentation through the angular distance of the resulting particle pairs. Charged EECs probe the energy flux carried by pairs of the same or opposite electric charges. The...
LHC Run 4 will provide additional challenges in the already demanding field of charged particle track reconstruction. The Inner Detector of the ATLAS experiment will be replaced by an all-silicon inner tracker (ITk) that will consist of Pixels and Strips providing greater coverage in pseudorapidity spanning up to 8 units. The ACTS Common Tracking Software (ACTS) is the toolkit of choice that...
In this work, we simulate $SU(3)$ color fields that
occur in the very early stages of
high-energy nuclear
collisions, using classical real-time lattice gauge theory. In particular, we model the structure of the proton and the longitudinal initial state fluctuations to simulate realistic non-boost invariant proton-nucleus collisions. We study the anisotropic momentum, and angular momentum,...
The innovative fixed-target programme initiated by the LHCb experiment during the LHC Run 2 has been enhanced for Run 3 with the introduction of a dedicated gas injection system, SMOG2. This upgrade features a gas cell to boost fixed-target luminosity and a new system that allows the injection of non-noble gases. SMOG2 enables the collection of large datasets from pA and PbA fixed-target...
Quarkonium production in high-energy lead-lead (Pb-Pb) collisions is a key tool for exploring both the perturbative and non-perturbative aspects of quantum chromodynamics (QCD) calculations.
Charmonia are bound states consisting of a charm and an anti-charm quark. Their production process can be divided into two stages: the creation of the heavy quarks and the formation of the bound state....
Balance functions have been used extensively to elucidate the time evolution of quark production in heavy-ion collisions. Early models predicted two stages of quark production: one for light quarks and another for the heavier strange quark, separated by a period of isentropic expansion. This led to the notion of clocking particle production and tracking radial flow effects that drive the...
The investigation of the properties of nuclear matter under extreme conditions is one of the main goals of the relativistic heavy-ion collisions. The analysis of transverse momentum spectra of produced particles provide insights into the particle production mechanisms as well as the freeze-out conditions of the system created in these collisions. We present the study of the kinetic freeze-out...
We explored the astrophysical properties of compact stars in the framework of renormalization Group (RG)-consistent three-flavor color superconductivity (CSC) using the Nambu-Jona-Lasinio (NJL) model with a Renormalization Group (RG)-consistent approach. We analyzed how variations in the vector interaction coupling ($\eta_V$) and diquark coupling ($\eta_D$) affect the equation of state (EoS),...
Multiplicity distributions in e+e- and proton-proton collisions analyzed via the combinants method 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 [1-5]. The set of combinants, Cj provides a similar measure of fluctuations as the set of cumulant...
Relativistic heavy ion collisions provide exciting new ways to probe nuclear structures. In this talk, we present model-to-data comparisons for the collisions of very-deformed nuclei (U+U collisions at $\sqrt{s_{NN}} = 193$ GeV) and slightly-deformed nuclei (Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV) at RHIC. For theoretical calculations, we use a multistage model consisting of...
Neutron Stars (NSs) make a unique physical laboratory with extreme physical conditions that are irreproducible in experiments and capable of inducing a hadron-to-quark deconfinement phase transition in their interior. Given the high densities reached by the cold nuclear matter in NSs, it is speculated that NS cores may contain deconfined quark matter (QM). State-of-the-art inputs from...
The equation of state of nuclear matter at 2-4 times nuclear saturation density is not very well determined by first principle methods. Heavy-ion collisions offer the opportunity to reach those high densities and collective flow measurements are sensitive to the properties of the medium. At 1-2 AGeV per nucleon beam energy transport approaches are the best choice for the theoretical...
The STAR experiment conducted isobaric collisions using $^{96}_{44}\text{Ru}+^{96}_{44}\text{Ru}$ and $^{96}_{40}\text{Zr}+^{96}_{40}\text{Zr}$ ions, offering a valuable opportunity to study Coulomb dissociation and investigate nuclear structure. Although these isobars have the same mass number, their differing proton and neutron numbers may lead to distinct charge distributions and neutron...
We present a calculation of the spin alignment for unflavored vector mesons in thermalized quark-gluon plasma based on the Kubo formula in linear response theory. This is achieved by expanding the system to the first order of the coupling constant and the spatial gradient. The effect strongly relies on the vector meson’s spectral functions which are determined by the interaction and medium...
Fluctuations of conserved charges, quantified by the cumulants of order $n$ ($\kappa_{n}$) of their distributions, are powerful observables to probe the QCD phase structure, including the search for the conjectured first-order phase boundary and the associated critical point. On the experimental side, RHIC has successfully completed the second phase of its beam energy scan programme, covering...
Compressed Baryonic Matter (CBM) is a heavy-ion physics experiment designed to probe the QCD phase diagram at high densities. It is being installed at the Facility for Anti-Proton and Ion Research (FAIR) in Darmstadt, Germany, and will use a beam from the new SIS-100 accelerator. The Silicon Tracking System (STS) is the core tracking detector of CBM, tasked with achieving high-precision...
The production of beauty hadrons in proton-proton (pp), proton-lead (p-Pb), and lead-lead (Pb-Pb) collisions offers critical insights into heavy-flavor hadrons production mechanisms across different collision systems. In pp collisions, beauty hadron production can be used to test the predictions of perturbative Quantum Chromodynamics (pQCD), providing constraints on parton distribution...
We present novel predictions for the heavy- and light-flavor nuclear modification factor $R_{AB}$ in small systems from a pQCD-based energy loss model, constrained by a comprehensive statistical analysis of central heavy-ion suppression data. Our large-system-constrained results are validated by their consistency with the light-flavor photon-normalized $R_{AB} \sim 0.75$ measured in central...
The use of neural networks in high-energy physics has rapidly expanded, particularly in jet tagging applications. This study explores two parallel methods, both leveraging convolutional neural networks (CNNs) to classify jets produced in high-energy collisions by differentiating between heavy quark (charm, bottom), light quark (up, down, strange), and gluon jets. The first method constructs...
In this contribution we present preliminary results on the dielectron production in p+p interactions at 1.58 GeV 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 conversion pair rejection. With this upgrade, a signal-to-background ratio...
We estimate the diffusion coefficient matrix for baryon number, strangeness, electric charge, and charm quantum numbers in an interacting hadron gas. For the first time, this study provides insights into the charm current and estimates the diffusion matrix coefficient for charmed states, treating them as part of a quasi-thermalized medium. We analyze the diffusion matrix coefficient as a...
The growing interest in the thermodynamic properties of strongly-interacting systems under rotation, particularly using lattice gauge techniques on the Euclidean manifold and with an imaginary angular velocity $\Omega = i \Omega_I$, has motivated the current study of Dirac fields under imaginary rotation. For $\nu = \beta \Omega_I / 2 \pi$ a rational number, the thermodynamics of free scalar...
Direct photon measurements provide essential insights into the properties and evolution of the quark-gluon plasma (QGP), from the early initial conditions through the pre-equilibrium stage to the QGP and hadronic phases. In the ALICE experiment, photons are reconstructed using two complementary methods: the photon conversion method, making use of the excellent tracking capabilities of ALICE,...
In this poster, the first measurement of direct photons at the transverse momentum of $1 < p_{{\rm T}} < 6$ GeV/$c$ at midrapidity $|\eta| < 0.8$ in inelastic and high-multiplicity proton--proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV is presented. The fraction of virtual direct photons in the inclusive virtual photon spectrum is obtained from a fit to the dielectron...
Studying hyper-nuclei yields and their collectivity can shed light on their production mechanism as well as the hyperon-nucleon interactions. Heavy-ion collisions from the RHIC beam energy scan phase II (BES-II) provide an unique opportunity to understand these at high baryon densities.
In this poster, we present the first measurement of directed flow ($v_{1}$) for $^{4}_{\Lambda}{\rm He}$...
ALICE data recorded from pp collisions at $\sqrt{\it s}=13$ TeV are analyzed to study the mean transverse momentum ($p_{\rm T}$) fluctuations. The study is motivated by the idea that non-monotonic changes in $p_{\rm T}$ correlations with varying energy, if observed, may be taken as an indicator for the QGP formation. The mean $p_{\rm T}$ fluctuations are studied in terms of the two-particle...
The concept of pseudo-gauge freedom, which is essential for defining conserved currents in effective field theories like relativistic hydrodynamics, continues to inspire significant debate and re-interpretation. In this talk, I will present recent insights that clarify the role and limitations of pseudo-gauge transformations and pseudo-gauge invariance in hydrodynamic systems.
For...
The study of event-by-event transverse momentum $<p_{T}>$ fluctuations and $p_{T}$ correlations between particles provide insight into the properties of the hot and dense matter created in Au+Au collisions at the Relativistic Heavy-Ion Collider (RHIC). These measures have been proposed as tools to understand the initial state geometry and subsequent evolution of the system as well as quantify...
In off-central heavy ion collisions (HIC), an appreciable amount of initial orbital angular momentum (OAM) of the colliding heavy nuclei can be transferred to the participants and subsequently to the nuclear medium formed [1]. This transferred OAM can give rise to local vorticity in the created matter. The transport coefficients of the matter formed in HIC give ample information about the...
In this talk, we will discuss the effects of color decoherence and virtuality evolution on jet quenching observed in relativistic heavy-ion collisions. First, we will show that the jet multiplicity, calculated according to the color coherence picture, provides a reasonable description of inclusive jet data up to $p_T \sim 1$ TeV in pp collisions at the LHC. Building on this understanding of...
Heavy-Quarkonia evolution in quark-gluon plasma (QGP) can be studied using the framework of open quantum systems. The density matrix of the quarkonia satisfies a simple Lindblad-type equation if one assumes that the binding energy $E_b$ is much smaller than the medium temperature $T$. This approximation does not hold for a significant part of the QGP evolution. We study the evolution of...
Elecromagnetic probes, such as dileptons, can provide a clear information about the properties of strongly interacting hadronic and partonic matter created in heavy-ion collisions since they are undisturbed by the strong final state interaction. The dileptons are emitted during the whole evolution of the expanding system from many different sources - from hadron decays to the quark-gluon...
Particle production in heavy-ion collisions exhibits a collective behaviour known as collective flow, which arises from the pressure-driven expansion of the quark-gluon plasma (QGP) formed in these collisions.
The second-order Fourier coefficient of a series expansion of the azimuthal distribution of final-state particles is known as elliptic flow ($v_2$). A non-zero $v_2$ can lead to the...
Hadronic resonances are crucial probes to understand the various phases of matter created during relativistic heavy-ion collisions. Due to their short lifetimes, the yields of these resonances can be affected by competing rescattering and regeneration mechanisms in the final hadronic phase. Rescattering can alter the momentum of the resonance decay products, limiting their reconstruction...
We present a systematic Bayesian analysis of Quark-Gluon Plasma (QGP) properties at finite baryon density using measurements of Au+Au collisions at the RHIC Beam Energy Scan program. The theoretical model simulates event-by-event (3+1)D dynamics of relativistic heavy-ion collisions with the state-of-the-art hybrid hydrodynamics and hadronic transport theory. We analyze the model's...
Understanding energy reconstruction in the forward rapidity region is crucial for the definition of collision centrality as well as for the measurements of jet suppression in the forward region. In this poster, we discuss the performance n the forward rapidity region of the ATLAS detector in 2023 and 2024 Pb+Pb data for both total energy reconstruction and jet reconstruction. Jet...
Jet substructure measurements, based on the distribution of final-state hadrons, offer insights into parton shower dynamics and hadronization. Observables such as the transverse momentum fraction ($j_\mathrm{T}$) and longitudinal momentum fraction ($z$) of jet constituents, provide valuable information on these processes. The ALICE collaboration has recently reported measurements of the...
NA61/SHINE is a multipurpose fixed-target experiment located at CERN SPS. One of its main goals is to study the onsets of fireball and deconfinement and the properties of strongly interacting matter. For this purpose, a unique two-dimensional scan in collision energy ($\sqrt{s_{NN}} = 5.1 - 17.3$ GeV) and system size was performed. Results for p+p, Be+Be, and Ar+Sc collisions were already...
Equation of State at finite density in external magnetic fields aiming for an experimental setup
Probing the QCD phase diagram is a challenging task both from a theoretical and an experimental standpoint. Moreover heavy ion collision experiments have shown, that strong magnetic fields arise, which may have a sizeable impact on the phase diagram. From the lattice QCD perspective the...
Mean transverse momentum ($ \langle \it{p}_{\rm T} \rangle$) fluctuations are dynamic indicators of system properties, arising from correlations among the transverse momenta of final-state particles, such as those due to resonance decays and jets. Consequently, event-by-event $ \langle \it{p}_{\rm T} \rangle$ fluctuations in pp collisions serve as a model-independent baseline to explore...
In ultrarelativistic heavy-ion collisions, several nontrivial physics phenomena (e.g. collective anisotropic flow, jet quenching, etc.) can lead to persistent event-by-event azimuthal anisotropies in particle distributions, which are traditionally quantified with Fourier harmonics $v_n$. Besides the conventional measurements of individual $v_n$ harmonics, further independent information about...
Exclusive photoproduction of vector mesons offers a valuable tool for probing the gluon distribution within nucleons . 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. Results from $J/\psi$ and $\Upsilon$(1S) mesons in pPb collisions at a...
Strangeness production is a key signature of the formation of a hot and dense medium in heavy-ion collisions. Understanding the production mechanisms across different system sizes remains a significant challenge in this field. Hybrid approaches, particularly those based on transport theory and hydrodynamics, such as the core-corona picture, have been successfully applied in previous...
Charge-dependent directed flow can reveal the influence of electromagnetic fields in heavy-ion collisions. For instance, Faraday induction is predicted to contribute negatively to $\Delta (dv_1/dy)$, defined as the difference in the slope of rapidity-odd directed flow ($dv_1/dy$), between positively and negatively charged particles. Recent STAR data from peripheral Au+Au collisions at...
The study of heavy quark (HQ) dynamics in the quark-gluon plasma (QGP) produced in heavy-ion collisions at facilities like RHIC and LHC has provided crucial insights into QGP properties. Due to their large masses, HQs evolve over the QGP’s short lifetime while retaining information about their interaction with the medium. Typically, HQ evolution is studied using the Langevin equation under the...
In high-energy collider physics, a key question is whether quark--gluon plasma (QGP) is formed in proton-proton (pp) collisions. Recent observations suggest that collectivity exists in pp collisions, although signatures of jet quenching would provide stronger evidence. This study examines jet quenching in pp collisions at two different beam energies: $\sqrt{s}=13$ TeV (LHC Run 2) and...
In this presentation, we investigate femtoscopy correlation functions to access the interactions of protons across various hadrons with different baryon numbers. Beginning with the proton-pion system, we apply the results of the unitarized chiral effective theory into the TROY (T-matrix-based Routine for HAdrOn FemtoscopY) framework to predict measurable correlation functions in...
Angular (ΔηΔφ) correlations of identified particles in ultrarelativistic proton-proton and heavy-ion collisions exhibit features dependent on collision systems and particle types. These characteristics stem from mechanisms such as (mini-)jets, elliptic flow, resonance decays, and conservation laws, with quantum statistics and final-state interactions influencing each particle pair’s unique...
Various approaches to exploring QCD Equation of State (EoS) using modern machine learning/deep learning techniques are presented. In the first part, various existing experimental measurements are used in a Bayesian framework [1] to constrain the density dependent potentials in UrQMD [2] for densities from 2 to 6 times saturation densities ($n_0$). It is shown that while the observables used in...
An enhancement of the strange baryon-to-meson yield ratio has been observed by ALICE for intermediate transverse momentum ($p_{\rm T}$) at high multiplicity from small to large colliding systems. This enhancement is possibly due to the effects of collective radial flow and recombination of quarks. However, there is ongoing debate regarding whether jet fragmentation could also play a role, as...
The 'ALICE 3' project is a proposed upgrade of the ALICE detector, which involves a complete replacement of the installation at Point 2. Crucial to the physics programme are high-precision measurements of heavy-flavour observables that require large data samples as well as state-of-the-art tracking performance. As a consequence, performance studies of the operating conditions of ALICE 3 that...
We study the linear sigma model coupled with dynamical quarks undergoing rigid rotation in unbounded Minkowski spacetime under the Tolman-Ehrenfest approximation. The thermodynamics of this rigidly rotating system induces, kinematically, an infinite local temperature state at the light cylinder, where the velocity of the system equals the speed of light. We show that the infinite-temperature...
Dileptons are excellent probes for studying the hot, dense hadronic matter created in heavy-ion collisions, as they do not participate in the strong interaction in the medium and carry undisturbed information from all stages of the fireball evolution.
In this contribution, we present preliminary results on anisotropic flow of di-electrons produced in Au+Au collisions at $\sqrt{s_{NN}}=2.23$...
Coherent photoproduction of vector meson (VM) in heavy-ion ultrapheripheral collisions (UPCs) is highly sensitive to the gluon distributions within heavy nuclei, making it a powerful tool for probing the nuclear gluonic structure. It is of particular interest for investigating nonlinear dynamics such as gluon saturation and nuclear shadowing effects in the small Bjorken-x region. The mass of...
Theory predicts that the inner structure of hadrons changes with increasing energy, and that gluon saturation can occur in heavy nuclei at lower energiescompared to protons. Additionally, phenomena such as gluon shadowing can exhibit similar experimental signatures to gluon saturation. ALICE has recently presented new results on coherent J/ψ mesons, where the photon probes the entire nucleus....
Quarkonia, which are bound states of heavy-flavor quark-antiquark pairs, have long been considered crucial probes for studying the quark–gluon plasma (QGP). In a simplified picture, the production of quarkonium is suppressed due to color screening within the QGP, formed during nucleus–nucleus collisions. A key observable in this context is the azimuthal anisotropy of quarkonia, providing...
The large angular momentum generated in non-central heavy-ion collisions contributes to the formation of vorticity within the medium, which subsequently induces polarization of particles with non-zero spin. The global polarization of Λ-hyperons near mid-rapidity increases at lower energies, which can be attributed to the correlation between angular momentum and enhanced baryon stopping. Recent...
The large minimum bias (MB) dataset of pp collisions at
√s = 13.6 TeV collected by ALICE during Run 3 provides an unprecedented opportunity to measure, for the first time, the transverse mass ($m_{\rm T}$) scaling of the femtoscopic source of proton–proton pairs as a function of the event multiplicity.
A common source size dependence on $m_{\rm T}$ , typically attributed to collective...
The measurement of open charm production is considered as an important tool for investigating the properties of hot and dense matter formed in relativistic nucleus-nucleus collisions and will allow for a model-independent interpretation of existing data [1].
The formation of hadrons containing charm quarks is particularly sensitive to quark-gluon plasma (QGP) creation. The NA61/SHINE...
The centrality estimation in proton-nucleus collisions at the LHC is typically based on measuring charged-particle multiplicity or zero-degree energy. The former, however, induces a bias on the hardness of the proton-nucleon collisions, resulting in deviations from the binary nucleon-nucleon scaling of hard processes. In contrast, the energy deposited at zero degrees, i.e. at forward...
We use the parametric approach to analyze jet suppression measured using the nuclear modification factor of inclusive jets and jets from gamma-jet events. With minimum model assumptions, we quantify the magnitude of the average energy loss, its pt-dependence, and flavor dependence. Further, we quantify the impact of fluctuations in the energy loss and nuclear PDFs on the measured jet...
To study the nature of collective phenomena in small collision systems, this contribution presents the measurement of the second harmonic of the anisotropic flow of heavy-flavor hadrons such as $D_0$ and $Λ^+_C$, also denoted as elliptic flow or $v_2$. The two-particle correlations method is used, where heavy-flavor candidates are correlated with hadrons.
Heavy-flavor candidates are...
The CERN ALICE Collaboration proposes the new ALICE 3 detection system to exploit the full potential of the HL-LHC for heavy-ion physics. The Forward Detector (FD) will be part of the ALICE 3 covering forward pseudorapidity 4 < |eta| < 7. FD will provide an interaction trigger, beam luminosity, initial vertex position, and a forward multiplicity. Its design should allow for smooth operations...
First results from the PHENIX experiment on the fraction of $J/\psi$ mesons at midrapidity region ($\mid \eta \mid <$ 0.35 ) coming from $B$-meson decay ($F_{B{\rightarrow}J/\psi}$) in $p$+$p$ collisions at $\sqrt{s}=$~200~GeV at RHIC will be presented. The measurement is performed using the central silicon vertex detector, which provides precise tracking and distance-of-closest-approach...
Event-by-event fluctuations in the number of different particle species produced in high-energy nuclear collisions encode essential information about the phase structure of the matter created in such collisions. In this contribution, we present a novel fuzzy-logic-based approach for reconstructing arbitrary-order moments of multiplicity distributions [1]. The proposed method provides a robust...
The states of matter produced in the early stage of heavy ion collisions can be highly anisotropic. If such a feature is sufficiently pronounced, one should expect the final particle distribution inside jets to reflect it in the form of non-trivial angle correlations. In this talk, we discuss a first step in exploring such correlations by studying how a $q\bar q$ state branching from an...
In this talk, we demonstrate that in smaller systems, such as proton–proton and peripheral ion–ion collisions, microscopic models for final state interactions, can produce anisotropies where the elliptic flow is negative — that is, the momentum is largest along the major axis, contrary to hydrodynamic predictions [1].
We present results from two distinct microscopic models: one based on...
We investigate the evolution of charm quarks in hot QCD matter within the well-grounded quasiparticle approach [1]. The quark-gluon plasma (QGP) is composed of the quasiparticle excitations with dynamically generated masses that are linked to the lattice QCD equation of state.
Utilizing the kinetic rate equation, we study the thermal production of charm quark pairs $(c\bar{c})$ in hot QCD...
We will present results for the heavy quark, i.e. top-right, corner of the Columbia plot. They were derived using a 1-loop Polyakov loop potential in the center-symmetric Landau gauge, supplemented by a minimal (1 parameter), phenomenological, Curci-Ferrari extension to the Faddeev-Popov terms, which we employ to account for the effect of Gribov copies. This model has been validated in the...
We use open charm production to estimate how far we can see back in time in high-energy hadron-hadron collisions. We analyze the transverse momentum distributions of the identified D mesons from pp, p–-Pb and A–-A collisions at the ALICE and STAR experiments covering the energy range from $\sqrt{s_{\rm NN}}$ = 200 GeV up to 7 TeV. While the low-momentum part of the spectra can be associated...
The early far-from equilibrium dynamics of the pre-hydrodynamic quark-gluon plasma (QGP) formed in heavy ion collisions can be characterized by distinct stages, during each of which the system loses some memory of its initial condition, until only the hydrodynamic modes remain. In QCD kinetic theory, this attractor behavior has been described in terms of self-similar scaling solutions for the...
Relativistic kinetic theory has been used to describe many aspects of relativistic heavy-ion collisions. To provide smooth initial condition for the hydrodynamic phase from the early stages. To take into account the interaction in the final stage of the evolution, before the chemical and kinetic freeze-out, or directly to replace hydrodynamics in the description of the strongly interacting...
A hybrid framework of spin hydrodynamics is proposed that combines the results of kinetic theory for particles with spin 1/2 with the Israel-Stewart method of introducing non-equilibrium dynamics. The framework of kinetic theory is used to define the perfect-fluid description that conserves baryon number, energy, linear momentum and spin part of angular momentum. This leads to the entropy...
Unravelling the hadronization mechanism in Quantum Chromodynamics (QCD) remains challenging due to its non-perturbative nature, often modelled in Monte Carlo event generators (such as PYTHIA and HERWIG) with parameters tuned to experimental data. While jets were originally proposed to circumvent non-perturbative effects and probe QCD at perturbative scales, we show that their substructure can...
Quarkonium production can be used to probe the matter formed in ultrarelativistic heavy-ion collisions. However, for theoretical understanding of the experimental results on quarkonium production in heavy-ion collisions it is necessary to know if and which quarkonium states exist above the crossover temperature, $T_c$ and what are the in-medium masses and widths of different quarkonium states....
We have estimated the induced electric field in quark-gluon plasma (QGP) due to its thermoelectric effects. At present, the relativistic heavy-ion collisions are capable of creating QGP, a locally thermalized medium composed of quarks and gluons.
During the space-time evolution of the QGP medium, interesting thermoelectric phenomena occur due to the presence of electrically charged particles...
In this work, we compare two multi-stage approaches for RHIC BES energies that both model the hot and dense part of the medium evolution with fluid dynamics, while have different strategies for the early-stage dynamics and baryon stopping. This work is important in the context of RHIC Beam Energy Scan program and future FAIR experiments, exploring the phase diagram of QCD and locating its...
There have been recent proposals that the speed of sound of the quark-gluon plasma can be measured from multiplicity and mean transverse momentum ($p_T$) measurements in ultracentral heavy-ion collisions, based on thermodynamics arguments and numerical simulations [1]. The CMS Collaboration has used this approach to extract values of the speed of sound remarkably consistent with lattice QCD...
The study of heavy-flavour hadrons in small systems, such as proton-proton (pp) collisions, offers insights into quantum chromodynamics (QCD) processes and allows us to deepen our understanding of the heavy-flavour quark parton shower and hadronisation processes. In a complementary approach to charm-tagged jets, measurements of azimuthal correlations between charm hadrons and charged particles...
Experimental data on the interaction between vector mesons and nucleons are a crucial input for understanding the pattern of in-medium chiral symmetry restoration (CSR) and dynamically generated excited nucleon states. However, accessing these interactions is hampered by the short lived nature of the vector mesons, making traditional scattering experiments unfeasible. In recent years the ALICE...
Relativistic heavy-ion collisions offer a unique environment for exploring quantum interference at an unprecedented femtometer scale through photon-nuclear interactions in photoproduction. In exclusive $\pi^{+}\pi^{-}$ production, the resonance and continuum $\pi^{+}\pi^{-}$ components arise from distinct production mechanisms in the $\gamma {\rm A}$ interaction. The continuum...
Two particle correlations have shown the presence of long-range rapidity correlations in small collision systems. Several other measurements provided insight into the unexpected collective behaviour similar to the one exhibited in heavy-ion collisions. These properties can be explained by several models, which consider a microscopic description like PYTHIA 8 and a macroscopic treatment as...
Precise measurements of charm-strange hadron production are crucial for validating perturbative QCD calculations based on the factorization approach. In particular, comparing production yields of strange and non-strange charm hadrons is essential for understanding heavy-quark hadronization in hadronic collisions and for constraining models with different quark hadronisation approaches.
In...
The transverse momentum spectra and their multiplicity dependence serve as key tools for extracting parameters to be compared with theoretical models. Over the past decade, the scientific community has extensively studied the possibility of a system analogous to quark-gluon plasma, predicted in heavy nuclei collisions, also existing in collisions involving light nuclei and protons. We have...
Quarkonium production in hadronic collisions is a complex process, driven by hard-scale phenomena, such as the creation of quark-antiquark pairs during the initial hard scatterings. Studying the ψ(2S) to J/ψ ratio as a function of charged particle multiplicity provides valuable insights into the mechanisms governing quarkonium formation in high-energy collisions. Since ψ(2S) is an excited...
The Standard Model describes ordinary hadrons, such as mesons (quark pairs) and baryons (three-quark structures). However, QCD predicts the existence of several exotic yet unseen states. These include two-quark, four-quark, molecular, hybrid states, and glueballs. In particular, the glueball, a unique bound state composed entirely of gluons, is particularly interesting. Lattice QCD...
Relativistic heavy-ion collisions in the few-GeV energy range provide an opportunity to investigate the properties of nuclear matter at high net-baryon densities, similar to the conditions in Neutron Stars (NS) and Neutron Star mergers. In recent decades, significant attention has been given to the presence of hyperons in NS and their influence on the Equation of State (EoS), which describes...
Virtual photons emitted from heavy-ion collisions preserve essential information about the fireball, where high baryon densities induce significant medium effects on the spectral function of vector mesons.
While short-lived $\rho$ mesons predominantly decay within the fireball, radiating thermal dileptons, a substantial fraction of $\omega$ mesons decay outside the fireball due to their...
Charmonium production in ultra-relativistic collisions is an essential probe for understanding the deconfined phase of QCD matter. The study of the production mechanism of charmonium states in pp collisions provides an opportunity to constrain both perturbative and non-perturbative aspects of QCD dynamics. In this context, measurement of charmonium polarization provides valuable insights into...
Understanding phase transitions in relativistic heavy-ion collisions provides insights into the properties of strongly interacting matter. Key transitions include the deconfinement phase, marked by fluctuations in conserved quantities, and the chiral phase, characterized by particle ratio fluctuations that indicate chiral symmetry restoration. Kaon isospin fluctuations were studied in Pb–Pb...
Photon-photon and photon-nucleus interactions in ultraperipheral collisions of nuclei lead to the production of a wide range of particle species, which can be
observed with relatively low backgrounds. The particle species produced include heavy quark and anti-quark pairs, dileptons, vector mesons such as J/psi, and potentially exotic hadrons. The unique geometry and instrumentation of the...
PHENIX has measured the centrality dependence of two-pion Bose-Einstein correlation functions in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The data are well represented by L\'{e}vy-stable source distributions. Three source parameters have been extracted as a function of transverse mass $m_T$ and centrality: the correlation-strength parameter $\lambda$, the L\'{e}vy index of stability...
In preparation for LHC Runs 5 and 6, the ALICE Collaboration has proposed a next-generation heavy-ion experiment, ALICE 3, which will be installed during the LHC Long Shutdown 4. This new experimental apparatus will feature exceptional pointing resolution and excellent Particle Identification (PID). A key component will be a Time-Of-Flight system utilizing silicon sensors, achieving an...
In ultra-relativistic heavy-ion collisions, copious rates of $\gamma\gamma$ processes are expected through the interaction of the large electromagnetic fields of the heavy nuclei. These can lead to light-by-light scattering via loop diagrams or photon-induced production of particles such as leptons or virtual axion-like particles. In ultra-peripheral collisions (UPCs), characterized by large...
Hypernuclei are objects composed of nucleons and hyperons. Measuring their properties and production provides insights into the force that binds strange hadrons to ordinary nucleons, which is poorly known. Additionally, measuring hypernuclei production in high-energy hadronic collisions offers a critical test for nucleosynthesis models, such as statistical hadronization and coalescence...
This talk presents a complete overview of ALICE measurements of $\pi^{0}$, $\eta$, and $\omega$ meson production in pp and p--Pb collisions using the Run 2 data, from $\sqrt{s}$ = 900 GeV up to 13 TeV, over an unprecedented transverse momentum range. The ALICE measurements of neutral meson production give constraints on parton distribution functions (PDF) and fragmentation functions (FF), and...
Collision of heavy nuclei at ultra-relativistic energies offer a unique opportunity to study the formation dynamics of light nuclei. Being loosely bound systems via residual strong interactions, their existence in the hot and dense medium, is very unlikely and possess interesting questions on their production mechanism in these energetic collisions. In the present contribution we will describe...
Measurements of collective flow of light- and hyper-nuclei in heavy-ion collisions at high baryon density regions is important for understanding the hyper-nuclei formation mechanism.
In this talk, we will present the results on collision energy and particle mass dependence of mid-rapidity directed flow $v_1$ of hyper-nuclei ($\Lambda$, $^3_\Lambda$H, $^4_\Lambda$H) and light-nuclei (p, d,...
Measurements of high-multiplicity proton-proton (pp) and proton-lead (p-Pb) collisions at the LHC have revealed that small collision systems show the onset of phenomena typical of heavy-ion collisions. Some of these signatures, such as strangeness enhancement and collective flow, suggest that light-flavor hadron production arises from complex mechanisms whose relative contributions evolve...
We present a systematic investigation of lepton pair production through photon-photon fusion processes in heavy-ion collisions. It is demonstrated that the dilepton production at a given impact parameter ($b_\perp$) with a fixed transverse momentum imbalance ($q_\perp$) can be factorized into a unified formula in terms of the Wigner photon distribution of heavy nuclei. We show that this...
The measurement of the Drell-Yan (DY) production at forward rapidity in proton-proton (pp) collisions at the LHC with the upgraded ALICE detector in Run 3 provides a unique tool for probing the PDFs and partonic structure of hadrons and nuclei. There is a lack of a hard and clear probe of nuclear matter at relatively small Bjorken-x (down to 10-5), which could provide information...
Dileptons are particularly valuable for investigating properties of hot and dense medium created in relativistic heavy-ion collisions. As they do not interact strongly with the medium, they carry undisturbed information about the QCD matter from which they are emitted.
By studying low-mass and low-momentum dileptons, we can gain insights into transport
properties and potentially uncover new...
Determining the luminosity of collisions delivered by the LHC is the goal of the ATLAS luminosity programme. An accurate luminosity measurement is fundamental for any physics measurement with the ATLAS detector, in PbPb collisions especially for high precision physics measurements, such as the $\gamma\gamma\rightarrow\mu^{+}\mu^{-}$ cross section in ultra-peripheral Pb+Pb collisions. In ATLAS,...
This work presents the study of the strange baryon balance function in proton-proton (pp) collisions at $\sqrt{s} = 13.6$ TeV at LHC with ALICE.
Balance functions of strange baryons are sensitive to production and transport of strange quarks and their hadronization to baryons during the evolution of hot QCD matter formed in heavy-ion collisions. They are also sensitive to the diffusion of...
The $\phi$ meson is an excellent probe of the partonic phase due to its small hadronic cross-section, making it less influenced by late-stage hadronic interactions compared to other hadrons. In the energy range of the STAR Beam Energy Scan II (BES II), the directed flow ($v_1$) of net-baryons has been suggested as a sensitive probe of the equation of state of hot and dense matter. The $\phi$...
The STAR Beam Energy Scan II (BES II) program at RHIC is crucial for exploring the phase structure of strong interactions and understanding the properties of quark-gluon plasma (QGP). Directed flow ($v_{1}$) has been suggested as a sensitive probe of the equation of state of hot and dense matter. The $\phi$ meson, with its mass close to that of the proton but with strange quark content...
The Quark-Gluon Plasma (QGP) produced in heavy-ion collisions can be studied using hard probes, such as $D^0$ meson-tagged jets created at early stage of the collision. The jet yield and its substructure are modified by interactions with the medium, compared to vacuum propagation. This phenomenon is known as jet quenching.
The generalized angularities $\lambda_{\alpha}^{\kappa}$...
The high-intensity beams provided by the CERN SPS in a wide energy interval offer a unique opportunity to investigate the region of the QCD phase diagram at high baryochemical potential. The NA60+ experiment, proposed for taking data with heavy-ion collisions at the SPS in the next years, has a strong potential for investigating the QCD phase diagram via measurements of electromagnetic probes...
A jet is a spray of collimated hadrons originating from the fragmentation of an energetic parton. In heavy-ion collisions, jets traverse the colored medium and lose energy via induced gluon radiation and elastic scattering, which modify jet yields and structure. When the overlap of the colliding nuclei is small, the transverse profile of the quark-gluon plasma (QGP) is expected to become more...
Dielectron production can occur in ultra-peripheral heavy ion collisions via the Breit-Wheeler process, in which the linearly polarized photons from the heavy ion fields interact to produce low transverse momentum dielectron pairs. This production is sensitive to the electromagnetic field distributions from the heavily Lorentz-contracted nuclei, which are directly dependent on the charge...
The simultaneous description of the elliptic flow and the production rate of direct photons in ultra-relativistic heavy-ion collisions remains a major theoretical challenge, commonly referred to as the “direct-photon puzzle”. To distinguish between the elliptic flow of direct photons and photons originating from hadronic decays, primarily from π0 mesons, a precise measurement of the π0 flow is...
In heavy-ion collisions, the Quark-Gluon Plasma (QGP) is created, and anisotropic flow is one of the critical measurements to understand the detailed medium properties of the QGP. The anisotropic flow of light and strange particles scales approximately with the number of constituent quarks. The scaling behavior is interpreted as the collective flow developing in the partonic phase. Resonance...
Studying heavy-flavor quarks can enhance our understanding of parton interactions with the Quark-Gluon Plasma (QGP). Due to their significant mass, heavy quarks (charm and bottom) are primarily produced during the early stages of high-energy heavy-ion collisions, where hard scatterings dominate, allowing them to experience the entire evolution of the QGP. One approach to investigate...
Quarkonia in high-energy proton-proton (pp) collisions are important probes for studying the quantum chromodynamics (QCD) in vacuum. Understanding the production mechanism of J/$\psi$, a bound state of a charm and anti-charm quark, is crucial to constrain both perturbative and non-perturbative aspects of QCD calculations. Different theoretical models have been developed aiming to describe the...
The STAR Collaboration reports the first measurements of the inclusive distribution of fully-reconstructed jets in peripheral (60-80%) and central (0-10%) Au + Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV at RHIC, using a dataset with an integrated luminosity of 5.2 nb$^{-1}$. The data were recorded in 2014 with an online High Tower trigger which requires at least 4.2 GeV energy...
Quarkonium are considered as an important tool to test our understanding of strong interaction as their production in hadronic collisions involve an interplay of both perturbative and non-perturbative aspects. A complete understanding of the production mechanism of quarkonia in elementary proton-proton collisions remains a challenge. None of the theoretical models of quarkonium production has...
This poster presents measurements of the di-jet momentum balance in heavy-ion collisions, focusing on anti-$k_t$ jets with varying radii ($R=$ 0.2, 0.3, 0.4, 0.5, and 0.6) using the ATLAS detector at the LHC. The analysis uses 1.72 $\mathrm{nb}^{-1}$ of Pb+Pb data collected in 2018 and 260 $\mathrm{pb}^{-1}$ of $pp$ data collected in 2017, both at a center-of-mass energy of...
Following a significant upgrade, the ALICE experiment resumed data-taking in 2022, collecting data at much higher interaction rates with continuous readout for most detectors. While ALICE’s Electromagnetic Calorimeter (EMCal) continues to operate in triggered mode, its photon and jet triggers allow for the full utilization of the LHC’s delivered luminosity. This increase in statistics enables...
Recent measurements of charm baryon-to-meson production-yield ratios at the LHC have shown a substantial enhancement of charm-baryon production in pp collisions as compared to electron-positron and electron-proton collisions. This evidence currently could be interpreted as a modification of the charm hadronization mechanism in hadronic collisions, disproving the assumption of universality of...
The directed flow ($v_1$) is a sensitive probe of the initial state conditions in heavy-ion collisions. One key initial condition is the presence of a strong electromagnetic field, which induces charge splitting between particles and antiparticles and has important implications for the QCD phase transition and the properties of the Quark-Gluon Plasma (QGP) [1]. Another crucial aspect of the...
Hard probe measurements in e+e− collisions are vital for comparative studies in proton-proton and heavy-ion environments, offering a clean reference free from hadronic initial state effects. The interest in N-point energy correlation functions (ENC) has been revitalized for studying QCD, due to their distinct resolution of scales that helps in exploring QCD from perturbative to...
We present a measurement of $\Upsilon$ polarization in PbPb collisions with the CMS detector. The results are obtained in the helicity and Collins-Sopper frames and compared with the corresponding measurements in pp collisions. Until now, all studies of quarkonium suppression in heavy ion collisions have assumed unpolarized production in the computation of the detection acceptance. The...
The production of $\pi^{0}$ and $\eta$ mesons in ultrarelativistic proton-proton (pp) collisions provides insight into the underlying Quantum Chromodynamics (QCD) processes that govern hadronization. Additionally, these measurements serve as an important baseline for the study of direct photons as well as dielectrons, both of which are crucial for understanding the dynamics of heavy-ion...
In this poster, we will present the first measurements of inclusive charged-particle jet spectra in various centrality classes in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.36$ TeV. In heavy-ion collisions, the measurements of jets traversing the hot medium provide critical insights into the Quark-Gluon plasma, which manifest themselves in jet energy loss and substructure modifications. The...
Quarkonium production in high-energy proton-proton (pp) collisions is an important tool for studying perturbative and non-perturbative aspects of quantum chromodynamics (QCD). Charmonia are bound states of charm and anti-charm quarks and their production process can be factorized into two stages: the heavy quark production and the formation of the bound state. The former happens within initial...
We report new ALICE measurements of inclusive charged-particle jet suppression and jet azimuthal anisotropy in Pb--Pb collisions. Inclusive charged-particle jet spectra in central Pb--Pb collisions at $\sqrt{s_{\mathrm NN}}$ = 5.02 TeV are measured over a broad kinematic range, including to very low jet $p_{\mathrm{T}}$, with jet resolution parameter up to 0.5, using event-mixing to correct...
Relativistic heavy-ion collisions generate extremely strong electromagnetic (EM) fields, providing an ideal environment to study the EM excitation of the vacuum. The Breit-Wheeler process, which involves the electron-position pair production via photon-photon interactions, represents the lowest-order decay mode of the QED vacuum excitation. This process was first observed by the STAR...
During the data-taking campaigns Run 1 and Run 2 of the Large Hadron Collider (LHC), the ALICE collaboration recorded a large amount of proton-proton (pp) collisions across a variety of center-of-mass energies ($\sqrt{s\,}$). This extensive dataset is well suited to study the energy dependence of particle production. Deep neural networks (DNNs) provide a powerful regression tool to capture...
We study the dynamics of a heavy quark propagating through strongly coupled $\mathcal{N}=4$ supersymmetric Yang-Mills (SYM) plasma. Concretely, we calculate the complete momentum broadening probability distribution due to interactions with the plasma. This calculation includes and goes beyond the classic results for the drag coefficient $\eta_D$ and momentum diffusion coefficients $\kappa_T$,...
The quark-gluon plasma (QGP) produced in ultrarelativistic heavy-ion collisions exhibits properties of a mostly perfect fluid. Experimentally, this was established by measuring azimuthal anisotropies in the final state, known as elliptic flow and higher order harmonics such as triangular flow. These Fourier harmonic coefficients have been extensively measured using inclusive charged particles...
Heavy flavour hadrons are key probes for the investigation of the initial stage as well as the evolution of the system created in heavy-ion collisions. In fact, the heavy quarks possess masses larger than the quantum chromodynamics (QCD) scale parameters and therefore are mainly produced in hard scattering processes with large momentum transfer $Q^2$. For the same reason, their production in...
Previous studies at RHIC and LHC observed that heavy flavor probe yields grow with the charged particle multiplicity of the collision. These measurements brought to the attention the importance of multi-parton interactions (MPI) in a single $p+p$ collision. Collisions with high activity can also produce an environment dense enough to break weak charmonium states, such as $\psi$(2S). The PHENIX...
The ALICE Collaboration commenced Run 3 with upgrades to the Inner Tracking System (ITS2) and the Time Projection Chamber (TPC), both pivotal for probing rare phenomena with unprecedented precision. The upgraded ITS2 enables higher tracking resolution, while the improvements to the TPC allow for continuous readout, significantly boosting resolution and data acquisition. Using these...
Neutron stars offer a unique possibility to study matter under extreme conditions. The core of such an object can reach densities up to several $n_0$ which enables the possibility for a transition to quark matter. However the properties of such hybrid stars could be mimicked by dark matter and thus one needs a clear understanding of the properties for each object. To do so we study dark...
In ultraperipheral Pb+Pb collisions, intense electromagnetic fields enable the generation of magnetic monopole pairs via the Schwinger mechanism. Due to their high ionization and unique trajectories in a solenoidal magnetic field, monopoles are expected to leave a large number of clusters in the innermost ATLAS pixel detector without associated reconstructed charged-particle tracks or...
Quarkonia are versatile tools to probe the dynamics of heavy quarks and of bound states at various scales in heavy ion collisions. While their prompt production rate mainly results from interactions between charm quarks and the medium constituents, the significant fraction of charmonia originating from the decay of B hadrons (nonprompt charmonia) offers a proxy for the behavior of beauty...
While fluctuations of the QGP initial conditions have been extensively studied in transverse plane, rapidity-dependent fluctuations remain a bit more elusive. In this talk, we present the new measures of fluctuations in the event-wise average transverse momentum, $\langle p_T \rangle$, which reflect event-by-event fluctuations of the size and entropy of the QGP initial source. We predict the...
Exclusive production processes in high-energy hadron collisions can be used to study both the gluonic structure of nucleons and the nature of exotic hadrons produced in these processes. The LHCb experiment is a unique tool for studying central exclusive production at the LHC. Recent central exclusive production measurements from LHCb will be presentend. These include studies of exclusive...
The study of particle production in heavy ion collisions provides an opportunity to investigate both the hadronic and deconfined phases of strongly interacting matter and the transition between them. By measuring changes in particle yields as a function of energy, one can explore the properties of matter at the phase transition. The NA61/SHINE experiment, a fixed-target project at the SPS...
In heavy-ion collisions, the differences in shape between the positive and negative pion transverse momentum spectra at low $p_T$ can be used to study the Coulomb final-state interaction. The charged pions, as the most abundantly produced and lightest species, are the particles most strongly influenced by the Coulomb field generated by the positive net-charge of the stopped participant...
The structure of the QCD phase diagram is a fundamental question in nuclear and particle physics. Recent works suggest the possibility of inhomogeneous phases, where key properties of quark matter such as the chiral condensate or number density adopt periodic spatial patterns. Although progress has been made in studying these phases within QCD-inspired models, direct analysis in full QCD...
The NA61/SHINE strong interaction program is based on systematic beam momentum scans (13$A$–150$A$/158$A$ GeV/$c$) involving light and intermediate-mass nuclei, ranging from proton-proton ($p$+$p$) to xenon-lanthanum (Xe+La) collisions. The program's primary scientific goals include the search for the critical point of strongly interacting matter and the investigation of phenomena related to...
Heavy quarks (HQ) are considered to be excellent probes of the hot QCD matter produced in the high-energy heavy-ion collisions. HQ diffusion coefficient is one of the fundamental transport properties of the hot QCD matter. In this work, we have calculated the HQ momentum ($\kappa$) as well as spatial ($D_s$) diffusion coefficients in an ambient background weak magnetic field via evaluating the...
The $p_T$-spectrum of the charged particles produced can be described through the fragmentation of color strings by assuming the Schwinger mechanism with heavy-tailed distributions describing the string tension fluctuations. In particular, we discuss the string tension fluctuations described by the $q$-Gaussian distribution and the one derived for the QCD-based Hagedorn function. As a result...
The equation of state (EoS) at finite baryon chemical potential remains an elusive target for direct lattice QCD calculations, constituting a highly challenging topic. To address this issue, we have developed a novel Deep-learning quasi-parton model, which is constructed using three deep neural networks, to capture the fundamental properties of hot and dense QCD matter. Each neural network...
The interactions between jets and the longitudinal-boosted quark-gluon plasma (QGP) lead to softer particles drifting away from the jet core, where high-$p_\mathrm{T}$ particles remain concentrated, resulting in an intra-jet asymmetry. Investigating this asymmetry, particularly at forward rapidities, offers a novel avenue to probe jet-medium dynamics. Using the PbPb and pp data at...
We present measurements of azimuthal acoplanarity based on direct photon ($\gamma$) and $\pi^{0}$-triggered semi-inclusive recoil jet distributions in central Au+Au and $p+p$ collisions at $\sqrt{s_{\rm NN}}=200$ GeV, using datasets with integrated luminosity of 3.9 nb$^{-1}$ and 23 pb$^{-1}$, respectively.
This observable may probe jet wake effects and Moliere scattering off of...
Unfolding, the process of correcting measured data for detector distortions, is essential for comparing collider experiments. As experimental measurements grow increasingly sophisticated, the demand for higher-dimensional unfolding methods has risen. Recently, machine learning (ML)-based unfolding approaches have emerged to address these challenges. In heavy-ion collisions, unfolding becomes...
In this talk, I will present our latest research building upon the findings of PLB 850 (2024) 138533, which demonstrated that the entropy current can be derived from first principles using the quantum statistical method, bypassing the need for assumed traditional local thermodynamic forms. Our study uncovers that the local thermodynamic relations, which have been conventionally used as...
In preparation to the LHC Run3, the LHCb gaseous fixed-target, SMOG, was upgraded to offer higher instantaneous luminosity by up to two orders of magnitude with respect to Run2, new gases, including non-noble ones such
as hydrogen, and an increased experimental accuracy. Since 2022, LHCb is working with two independent collision points and as a collider and a fixed-target
experiment...
Particles produced in high-energy collisions (e.g. protons on protons) are described by power-law distributions. One such power-law distribution used extensively in the phenomenological studies originates from the nonadditive statistical mechanics proposed by C. Tsallis. In this report, we describe a nonadditive generalization of the conventional Bose-Einstein distribution using a single-mode...
Correlated electron-positron pairs (dielectrons) present a unique probe to study the properties of the medium created in relativistic heavy-ion collisions. They are produced in all stages of the collision and leave the system without loss of information as they do not interact strongly with the medium. However, at LHC energies, the thermal dielectrons emitted in the early stages of the...
A new high-precision forward calorimeter (FoCal) will be installed in the ALICE experiment at the LHC during Long Shutdown 3 for data-taking during LHC Run 4, currently scheduled for 2030-2033. FoCal consists of a Si+W sampling electromagnetic calorimeter with longitudinal and transverse segmentations (FoCal-E) and a conventional Cu+scintillating-fiber hadronic calorimeter (FoCal-H). FoCal has...
Lattice QCD calculations predict that a strongly-coupled QCD matter, the quark-gluon plasma (QGP), can be formed in relativistic heavy-ion collisions at extremely high temperatures and energy densities. Due to their large masses, heavy quarks ($c, b$) are predominantly produced in the initial hard scattering process before the hot QCD medium forms. Their final-state dynamics, therefore, encode...
We discuss the effect of rotation on the confining and chiral properties of QCD using the linear sigma model coupled to the Polyakov loop in an attempt to resolve discrepancies between the first-principle based numerical and model-based analytical results. Working in a homogeneous approximation, we obtain the phase diagram at finite temperature, baryon density, and angular frequency. We...
The substructure of bottom quark jets is of substantial interest, both in vacuum and in medium, in terms of understanding radiation emitted from heavy quarks. Unfortunately, the decays of b hadrons, which are typically cascading, obscure the parton level branching, by filling the radiative dead cone. To circumvent this, one may study exclusive b-hadron decays, but one then sacrifices the vast...
In ultra-peripheral collisions (UPCs), coherent J/$\psi$ photoproduction has been recognized as one of the most sensitive probes of the gluon structure in nucleons and nuclei. Recently, STAR published differential measurements on photoproduced J/$\psi$ in ultra-peripheral d+Au and Au+Au collisions at $\sqrt{\mathrm{s_{NN}}}$ = 200 GeV. These results provide important constraints on gluon...
The measurement of dijets in proton-lead collisions at the LHC provides unique possibilities for investigating both nuclear and nucleon initial state effects as a function of parton scattering kinematics. In particular, color fluctuation effects can significantly alter the average interaction strength of the proton, biasing the number of nucleon-nucleon interactions with the Pb nucleus and,...
The production of light (anti)nuclei is typically investigated by comparing experimental data with phenomenological models implementing statistical hadronization or coalescence approaches. In this context, the ALICE experiment has performed a broad set of precision measurements in different collision systems (pp, p-Pb and Pb-Pb) since the beginning of its operations. In this contribution, the...
In proton-proton (pp) collisions, the ratio of strange to non-strange hadron yields is observed to increase smoothly with the multiplicity of charged particles produced in the event. In high multiplicity pp collisions, such ratios are comparable to those measured in Pb–Pb interactions at similar multiplicities. The microscopic origin of this phenomenon in pp collisions has yet to be...
The interaction among nucleons and double-strange $\Xi^-$ baryons is an important ingredient for the equation of state of neutron stars.
In classical experimental methods, information on the strangeness S=-2 sector is accessed by measuring the binding energy of a $\Xi^-$ hyperon to a nucleus in so called hypernuclei. However, it is difficult to obtain large statistics with such experiments...
We exploit a jet substructure observable called the Lund Jet Plane (LJP) to map the momentum and angular orientation of particle emissions from a jet-initiating quark in order to study the jet evolution. This approach is useful for probing the Dead Cone phenomenon, a predicted suppression of soft gluon radiation in a conical region around the forward axis of a radiating massive quark. We...
Azimuthal anisotropy quantified as anisotropic flow coefficients are important observables that can provide key information about the collectivity of the system formed during heavy-ion collisions. The anisotropic flow coefficients are sensitive to both the geometrical configuration of the collision overlap region and the transport properties of the medium. Recently, hints of collectivity in...
One of the major motivations for the planned p--O and O--O collisions at the LHC is to explore the possibilities of small system collectivity. Such transverse collective expansion results in the appearance of long-range azimuthal correlation and is quantified via the coefficients, $v_{\rm n}$, of Fourier expansion of the azimuthal momentum distribution of the final-state particles. These flow...
Hypernuclei are bound states of nuclei with one or more hyperons. Hypertriton $\rm {}^{3}_{\Lambda}H$ ($np\Lambda$) and $\rm {}^{4}_{\Lambda}H$ ($nnp\Lambda$) are the two simplest observed hypernuclei. The $\rm {}^{3}_{\Lambda}H$ is the loosest bound hypernucleus, with a $\Lambda$ binding energy of $\sim$0.1 MeV, while the $\rm {}^{4}_{\Lambda}H$ is more strongly bound, with a $\Lambda$...
The event classifiers based on particle multiplicity or event topologies such as transverse spherocity and underlying events have been extensively used at ALICE to probe the origin of the observed Quark-Gluon Plasma (QGP) like phenomena in high multiplicity proton-proton (pp) collisions. The drawback of using the multiplicity-based classifiers is that selecting high multiplicity events may...
The studies of the production of light nuclei, such as deuteron, triton, and helium nuclei in heavy-ion collisions, are essential for understanding the dynamics of nuclear matter under extreme conditions. In addition, the yields of light nuclei and their ratios serve as an effective method for distinguishing between the thermal and coalescence models. The significantly larger datasets from the...
The Transition Radiation Detector (TRD) is one of the detector
components of the CBM expriment at FAIR, currently under construction.
Multi-Wire Proportional Chambers (MWPCs) with sizes of
$99\;\textrm{cm~x~} 99\; \textrm{cm}$ and $57\;\textrm{cm~x~}
57\;\textrm{cm}$ will record particle rates up to $120\;\textrm{kHz
cm}^{-2}$: the MWPCs are therefore designed to provide fast signal...
The ALICE experiment changed its data-taking strategy from triggered to continuous detector readout and underwent several detectors upgrades, in order to cope with the LHC Run3 luminosity increase and maximize the amount of data collected. Among the aforementioned upgrades, the installation of the new muon forward tracker (MFT) enriches the study of quarkonium production previously carried out...
This talk presents new measurements of prompt photon production in pp and p--Pb collisions by ALICE. We present the first determination of the nuclear modification factor of isolated prompt photon production in p--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. Together with a recent analysis at $\sqrt{s_{\rm NN}}$ of 8.16 TeV, this new measurement constrains the low-$x$ structure of matter...
A net baryon density up to 2-6 times the nuclear saturation density and high magnetic fields are expected in the reaction zone of upcoming CBM/NICA experiments. Such densities are also likely in the core of massive neutron stars, possibly with mixed quark-hadron phases. The chiral effective model, based on the principles of chiral symmetry breaking and broken scale invariance, is employed to...
The matrix model for the two-color QCD coupled to a single quark (matrix-QCD$_{2,1}$) exhibits novel features, such as the Pauli-Gursey symmetry. Using variational methods, we numerically investigate matrix-QCD$_{2,1}$ in the limit of ultra-strong Yang-Mills coupling ($g_{YM} =\infty$). The spectrum of the model has superselection sectors labelled by baryon number $B$ and spin $J$. We study...
The NA60+ experiment, proposed for data taking in the next years, aims to explore the high baryochemical potential region within the QCD phase diagram, exploiting the high-intensity beams from CERN SPS. Through a beam-energy scan involving Pb-Pb and p-A collisions in the range 6.3 < $\sqrt{s_{NN}}$ < 17.3, NA60+ is ideally positioned to access the high $\mu_B$ region of the QCD phase...
The study of quarkonium production in high-energy proton-proton (pp) collisions allows the investigations of both perturbative and non-perturbative aspects of quantum chromodynamics (QCD). Charmonia states, which are bound states of charm and anti-charm quarks, are produced via a process that can be factorized into two distinct stages: the generation of heavy quarks, followed by the formation...
We present a detailed numerical and analytical study of the out-of-equilibrium dynamics of Model G, the dynamical universality class relevant to the chiral phase transition. We quench the system from the high temperature, unbroken phase to the broken phase and study the real-time dynamics of the Goldstone modes, i.e. pions. Strikingly, the non-equilibrium evolution of the two-point functions...
Fluctuations of conserved quantities are proposed as a useful observable to study the QCD phase structure including the search for the first-order phase boundary and critical point [1]. Lattice QCD calculations have shown that there is no critical point for baryon chemical potential $\mu_B \le $ 450 MeV and a few phenomenology models calculations have shown that the critical point could be at...
Weakly coupled QCD kinetic theory can well describe the non-equilibrium evolution of the Quark-Gluon Plasma in the early stages of high-energy nuclear collisions. Previous studies in homogeneous and boost invariant systems have shown rapid hydrodynamisation and entropy production during the first $1~\text{fm}/c$. In this work, we relax the assumption of boost invariance and study the early...
In this work, we study the real-time dynamics of scalar field theory towards thermalization at finite temperature. We first evaluate thermal expectations for observables such as energy density and pressure at finite temperature to extract the property of the system at thermal equilibrium. Specifically, we formulate the scalar fields with both free and $\phi^4$ interaction components and...
The Compressed Baryonic Matter (CBM) experiment, being built at the Facility for Antiproton and Ion Research (FAIR)[1] accelerator complex in Darmstadt, Germany, aims to study the phase diagram of strongly interacting matter in the realm of high net baryon densities and moderate temperatures. The SIS-100 accelerator ring at FAIR will deliver accelerated ions up to beam kinetic energies 29 GeV...
Utilizing Zubarev's nonequilibrium statistical operator, we derive the second-order expression for the dissipative tensors in relativistic spin hydrodynamics, namely the rotational stress tensor ($\tau_{\mu\nu}$), boost heat vector ($q_\mu$), shear stress tensor ($\pi_{\mu\nu}$), and bulk viscous pressure ($\Pi$). The emergence of the first two terms, $\tau_{\mu\nu}$ and $q_\mu$, is attributed...
We argue that the actual production mechanism of deuterons and larger nuclear clusters - coalescence or direct thermal production - can be resolved with the help of elliptic flow. Coalescence is sensitive to the spatial extension of cluster wave function and therefore reflects the change of the size of producing homogeneity region when looking at cluster production in different azimuthal...
Heavy-ion experiments provide a new opportunity to gain a deeper understanding of the structure of nuclei. To achieve this, it is crucial to identify observables under circumstances that are minimally affected by the process that leads to the initial state of heavy-ion collisions from nuclear wave function. In this talk, we demonstrate that when assuming scale invariance, the effect of this...
Understanding the many-body properties of ground-state light nuclear shape, is a key question to further study initial conditions and collectivity in high-energy small system collisions at RHIC and the LHC. In this talk, we interface insights from ab initio nuclear structure calculations of $^{16}$O geometry with simulations of high-energy $^{16}$O+$^{16}$O collisions. Bulk observables, such...
The coherently produced vector meson in ultraperipheral collisions (UPCs) at high energies serves as a powerful tool for probing the nuclear gluon density. We are studying the production cross section of $\rho^{0}$ mesons in PbPb UPCs at $\sqrt{s_{NN}}$ = 5.36 TeV, having an integrated luminosity of 1.68 $\mu b^{−1}$, with the CMS detector. The contributions from the continuum and the resonant...
The recent spin polarization measurement of $\Lambda$-hyperons by the STAR and ALICE Collaboration has created a remarkable interest in the nuclear and high energy physics community to investigate the possible sources for hyperon polarization. It is suggested that in peripheral heavy ion collisions, the initial orbital angular momentum (OAM) manifests the vorticity, which primarily accounts...
The existence and location of the QCD critical point are objects of both experimental and theoretical studies. The comprehensive data collected by NA61/SHINE during a two-dimensional scan in beam momentum and system size allow for a systematic search for the critical point - a search for a non-monotonic dependence of various correlation and fluctuation observables on collision energy and size...
Significant efforts have been made within the heavy-ion collision community to locate the QCD critical endpoint (CEP). Recent lattice QCD studies using imaginary chemical potentials, based on simulations at temperatures above 120 MeV and utilizing Lee-Yang edge singularities in the complex chemical potential plane, suggest that the critical temperature at the CEP, $ T_c^{CEP}$, should be...
The studies of heavy flavor (charm or bottom) hadrons in relativistic collisions provide an undisputed testing ground for the theory of strong interactions, quantum chromodynamics (QCD). As the majority of the heavy flavor particles are produced in the initial stages of the heavy-ion collisions, they experience the whole QCD medium evolution. The lightest open charm meson, $D^{0}$, and hidden...
Searching dark portal particle is a hot topic in particle physics frontier. We present a simulation study of an experiment targeted for searching the scalar portal particles and vector portal particles at Huizhou $\eta$ factory. The HIAF high-intensity proton beam and a high event-rate spectrometer are suggested for the experiment aimed for the discovery of new physics. Under the conservative...
The ALICE Experiment will upgrade the innermost three layers of its Inner Tracking System (ITS) during the next LHC Long Shutdown (LS3). It is planned to partially replace the existing conventional setup using individual chips on staves by a novel concept, where wafer-scale sensors are bent to half-cylinders allowing for a tracker with an extraordinarily low material budget of $0.07\%~X/X_0$...
The Anderson-Witting relaxation-time approximation (RTA), providing a simple approximation of the Boltzmann collision integral, suffers from the drawback that the single relaxation time $\tau_R$ controls all transport coeffcients (shear and bulk viscosities, diffusivity, higher-order coefficients) [1]. Our Shakhov-like extension systematically introduces extra parameters allowing the...
Shear and bulk viscosities are two key transport coefficients that characterize the fundamental properties of quark-gluon plasma. They quantify the response of the energy-momentum tensor to the shear flow and divergent flow, serving as crucial input parameters for the phenomenological and transport models that interpret experimental data, e.g. the elliptic flow $v_2$.
However,...
Two-particle correlation functions of hadrons are sensitive to mechanisms of particle production and transport in elementary particle collisions. The production of quarks is determined by coupling terms of the QCD Lagrangian. These nominally conserves quark flavors in addition to energy, momentum, and electric charge: flavor currents are conserved at the level of quarks and gluons. The...
SiPM (Silicon PhotoMultiplier) sensors are one of the technologies under study for the outer timing layer of ALICE 3, a next-generation multipurpose detector at the LHC which will replace the present ALICE experiment for Run 5 and beyond.
SiPMs are usually coupled to scintillators or Cherenkov radiators. Nonetheless, in recent studies it has been shown that SiPMs can directly detect charged...
We show analytically that the small system corrections to thermodynamics quantities such as pressure and energy density are large, order 30%, for massless free scalar field theory in systems of size and temperature relevant for high-energy nuclear collisions. These analytic expectations are confirmed by quenched lattice QCD calculations of pressure and energy density in an anisotropic system...
Relativistic viscous hydrodynamics has been widely used as an effective theory of the quark-gluon plasma (QGP) stage in high energy collisions. The analytical structure of hydrodynamics consists of a hydrodynamic and a non-hydrodynamic mode. The hydrodynamic mode is associated with an attractor solution and is considered to be the reason for the unreasonable effectiveness of hydrodynamics in...
Understanding the properties of hypernuclei helps to constrain the interaction between hyperon and nucleon, which is known to play an essential role in determining the properties of neutron stars. Experimental measurements have suggested that the hypertriton ($^3_\Lambda \text{H}$), the lightest hypernucleus, exhibits a halo structure with a deuteron core encircled by a $\Lambda$ hyperon at a...
Theoretical modelling of the neutron and proton ZDC signals in heavy ion collisions is in its infancy due to its unique dynamics of spectator nucleons. Spectators, often forming clusters with varying charge-to-mass ratio, may fail to reach either ZDC and also single proton spectators are challenging to model due to the beamline magnetic fields. Despite these challenges, spectator production...
The conventional weakly-coupled description of finite-temperature plasmas lead to the appearance of quasi-particles with thermal masses. By incorporating contributions from both the (chromo)electric scale $gT$ and (chromo)magnetic scale $g^2T$, we establish thermal sum rules of quark spectral function for strongly-coupled QCD that respect Fermi-Dirac statistics as required by quantum...
sPHENIX, located at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, is a multipurpose proton and ion collider detector, and a central piece of its physics program is the measurement of open heavy flavor production in both pp and AuAu collision systems. Production of D mesons, both prompt and as cascade decays from B mesons, provide clean probes of the Quark Gluon Plasma....
sPHENIX is a next-generation, state-of-the-art particle detector at the Relativistic Heavy-Ion Collider (RHIC) that has recently completed full commissioning of its subsystems with datasets of 200 GeV Au+Au and p+p collisions during the 2023 and 2024 commissioning runs. From this inaugural dataset, the anisotropic flow (v_n) of charged hadrons has been measured for the first time in the...
The sPHENIX experiment is a next-generation collider detector at RHIC designed for rare jet and heavy flavor probes of the Quark-Gluon Plasma and polarized proton-proton collisions. sPHENIX includes large-acceptance electromagnetic and hadronic calorimetry, the latter of which for the first time at RHIC, as well as a four-subsystem precision tracking system comprising a MAPS-based silicon...
The objective of electron identification (eID) in the sPHENIX experiment is to accurately distinguish electrons from quarkonium (such as J/psi and Upsilon) di-electron decay events while effectively suppressing hadron background, thereby enhancing the signal-to-noise ratio crucial for studying Upsilon and J/psi suppression within the Quark-Gluon Plasma. We compare traditional cut-based methods...
Accurate measurements of $J/\psi$ production are crucial to advancing the heavy flavor program in sPHENIX. During Run 2024, sPHENIX has collected 13pb$^{-1}$ of data, utilizing both tracking and calorimetry detectors with 1.5mrad crossing angle and $|z_{vertex}|<10~$cm in 200GeV $p+p$ collisions. Experimentally, it remains a challenge to measure $J/\psi$ particles due to the low production...
We investigate the event multiplicity dependence of heavy-flavor jet production in p+p collisions at RHIC, focusing on the role of multi-parton interactions (MPI). Due to differences in mass and color charge, heavy-flavor jets are expected to fragment differently from jets originating from light partons. While jet quenching, a key signature of the quark-gluon plasma in AA collisions, is...
The sPHENIX experiment is a next-generation collider detector at RHIC designed for rare jet and heavy flavor probes of the Quark-Gluon Plasma. With ever-increasing collision rates producing larger data volumes and the search for rarer physics processes, it is becoming apparent that autonomic decision making can play a key role in tagging physics events of interest to specific groups or...
The sPHENIX experiment is a state-of-the-art detector at the Relativistic Heavy Ion Collider
(RHIC) which represents the first detector with both electromagnetic and hadronic
calorimeters with full azimuthal coverage and wide rapidity acceptance centered at
midrapidity, thus making it well suited to measure jets. This poster presents a study of
calorimeter energy-energy correlator at 0.1 <...
There is considerable evidence suggesting the existence of QGP droplets even in small collision systems, such as p+p and p+A collisions. Measurements of long-range correlations are important to evaluate the interplay between the role of initial and final state effects. The sPHENIX experiment at RHIC began operations in 2023 and took p+p collision data over a period of five months in 2024. In...
The sPHENIX experiment is a next-generation collider detector at RHIC designed for rare jet and heavy flavor probes of the Quark-Gluon Plasma. The experiment includes large-acceptance, electromagnetic (EMCal) and hadronic (HCal) calorimeter systems, along with a very high-rate data acquisition plus trigger system. In RHIC Run-24, sPHENIX sampled 107/pb of p+p collision data at 200 GeV using an...
The sPHENIX experiment is a next-generation collider detector at RHIC designed for rare jet, photon, and heavy flavor probes of the Quark-Gluon Plasma. The experiment includes large-acceptance, hermetic electromagnetic (EMCal) and hadronic (HCal) calorimeter systems, along with a very high-rate data acquisition plus trigger system. In RHIC Run-24, sPHENIX sampled 107/pb of p+p collision data...
Machine learning models have previously been utilized to address the challenge of subtracting combinatorial backgrounds from jets in heavy-ion collisions, with most earlier efforts focusing on supervised regression models. In this talk, we introduce the first self-supervised application of a generative AI model for jet background subtraction. We utilize UVCGAN [1], a Cycle Consistent...
D-meson production measurements in pp collisions are used to test perturbative quantum chromodynamics (pQCD) calculations. This contribution reports preliminary results of the ALICE Collaboration on the non-prompt $\text{D}^0$ fraction at midrapidity in the transverse-momentum range $p_\text{T} < 24$ GeV/\textit{c}, measured in pp collisions at $\sqrt{s} = 13.6$ TeV, using data from the LHC...
Luminosity determination in ALICE is based on the van der Meer (vdM) scan procedure. The vdM scan data in Run 3 are collected through subsystems such as Fast Interaction Trigger (FIT), Zero Degree Calorimeter (ZDC), and Inner Tracking System 2 (ITS2). In the vdM scan, the two beam bunches are moved in opposite directions along the horizontal or vertical axis. The visible cross section is...
NA61/SHINE is a multi-purpose, fixed-target hadron spectrometer at the CERN SPS. Its research program includes studies of strong interactions as well as reference measurements for neutrino and cosmic-ray physics. A significant advantage of NA61/SHINE over collider experiments is its extended coverage of phase space available for particle production. This includes the entire projectile...
Shock waves in matter produced under extreme conditions drive complex processes like energy transfer, particle acceleration, and plasma instability. Magnetic fields alter the shock wave properties of matter produced in heavy ion collisions and astrophysics, influencing energy density, pressure, and turbulence in these extreme conditions. How magnetic fields impact shock wave evolution in both...
The measurements of Lambda transverse polarization, i.e. the polarization in the direction transverse to the lambda production plane, have a long history. The unexpected observation of significant Lambda hyperon polarization in inclusive p+p and p+A collisions using unpolarized beams triggered theoretical efforts to describe this effect. Numerous models have been proposed to explain the origin...
Entanglement Enabled Spin Interference (EESI), an example of the Cotler-Wilczek process, was used to measure the structure of nuclei and neutron skins in ultraperipheral (UPC) Au+Au and U+U collisions. Study of the interference in peripheral collisions provides novel information on the impact parameter dependence, the entanglement criteria, and wavefunction decoherence. On one hand, the medium...
Heavy quarks are formed in the earliest stages of heavy-ion collisions and hence carry comprehensive information about the entire evolution of the initial non-equilibrium glasma phase to a quark-gluon plasma phase, its subsequent hydrodynamic evolution and hadronization at later stages. One of the quantities of interest to model this evolution and to compare with experimental observations is...
A new observable, ST , is introduced in terms of the sum of the transverse momentum of charged particles (Sum pT i ) produced in proton proton (p−p) collisions at LHC energies to probe the underlying events (UE). The UE are defined as those aspects of p−p collisions that are not attributed to the primary hard scattering process, but rather to the accompanying interactions of the rest
of the...
We present a comprehensive differential study of $\Lambda$ hyperon polarization in Au+Au collisions at low and intermediate energies and different impact parameters, employing the microscopic transport model UrQMD in conjunction with the statistical hadron-resonance gas model. We show that in central collisions the resulting thermal vorticity configuration effectively manifests as the...
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 ratios of resonances to...
The femtoscopy technique, applied to nucleus-nucleus collisions, is a powerful method for studying the properties of particle-emitting sources and providing precise insights into the final-state interactions of the produced hadrons. Through femtoscopy data analysis, key conclusions can be drawn about the existence of bound states, the nature of molecular states, and even the dynamics of...
The angular correlation function is a key tool in the study of hadronization mechanisms. Several effects influence these functions, including quantum statistics, final state interactions, energy and momentum conservation, resonance decays and the quark composition of the interacting particles. This serves as a powerful tool for checking the validity of the theoretical models.
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To quantify the properties of hadronic collisions at LHC energies, a precise understanding of the system's spatial and temporal evolution is essential. Femtoscopic correlations provide a powerful tool for measuring the size of the homogeneity region at kinetic freeze-out. In this analysis, we measure femtoscopic correlations within jets produced in proton-proton collisions at $\sqrt{s} = 13$...
In relativistic heavy-ion collisions at the LHC, the quark-gluon plasma (QGP) is produced. The transition is achieved when the system reaches a specific critical temperature ($T_{\mathrm{ch}}$). Lattice QCD calculations indicate that chiral symmetry (CS) restoration occurs around $T_{\mathrm{ch}}$ as well ($\sim 156$ MeV). CS restoration can be investigated using resonances that are parity...
We employ a variational quantum algorithm to study the chiral condensate of 1+1 dimensional SU(2) non-Abelian gauge theory at different temperatures and chemical potentials. Our algorithm is tested both by classical simulations and on real quantum computers. We observed the breaking and restoration of chiral symmetry. Our simulation results are in good agreement with theoretical calculations...
We investigate the interplay between saturation dynamics and fluctuating hotspots on midrapidity flow observables in Pb+Pb collisions at the LHC energies using the new Monte Carlo EKRT (MC-EKRT) initial-state event generator [1,2]. We demonstrate that this type of analysis can be efficiently and accurately performed using pre-trained neural networks [3] to predict flow observables directly...
Exotic hadrons, such as tetraquarks, fall outside the traditional classification of mesons and baryons. Their production mechanisms remain poorly understood, although statistical, hydrodynamical, and coalescence models have attempted to predict their behavior. The first observation of such a particle was made by the Belle Collaboration in 2003, with the discovery of the X(3872). This study...
Space–time properties of particle-emitting sources created in heavy-ion collisions can be studied with femtoscopic techniques using momentum correlations based on quantum statistics, Coulomb and strong interactions. In this talk, the most recent results of femtoscopic analysis of identical proton pairs in Pb--Pb collisions at $\sqrt{s_{\textrm{NN}}}$ = 5.36 TeV based on data collected by ALICE...
Recent measurements in pp and p-Pb collisions at the LHC showed that the production of light-flavour hadrons relative to pions increases with the charged particle multiplicity of the event already in small systems. This smooth evolution connects different collision systems almost independently of the collision energy. This extends to the strangeness sector, where the enhanced production of...
Strangeness production serves as a sensitive probe of the properties of the quark-gluon plasma (QGP). In particular, it is proposed that the $\Omega/\phi$ ratios in different colliding systems may reveal the minimum colliding system size required to produce the QGP. In Au+Au collisions at $\sqrt{s_{\text{NN}}}$ = 200 GeV significant $\Omega$ enhancement over $\phi$ has been observed at...
The ALICE Forward Calorimeter (FoCal) detector upgrade is designed to probe hadronic matter, its gluon density and the parton distribution functions at Bjørken-$x$ in the order of and smaller than 10⁻⁶. Located 7$\,\mathrm{m}$ away from the LHC interaction point, it will cover a pseudo-rapidity range of 3.2 < η < 5.8. The calorimeter will be composed of a 20-layer Si-W sampling electromagnetic...
We calculate several observables probing jet phenomena in heavy-ion collisions that propagates JEWEL medium-modified parton showers in event-by-event (2+1)D v-USPhydro profiles with $\rm T_RENTo$ initial conditions. The jet-hydro interface incorporates finer features from the hydrodynamic calculation, such as local fluid velocity and the applied equation of state, to realistically simulate...
An excess of charged versus neutral kaons has been recently reported by the NA61/SHINE collaboration. Similar excesses were also present in previous experiments, even if with larger errors. Models for hadron productions in heavy ion collisions systematically underestimate the measured charge-to-neutral kaon ratio. In fact, using well-established models for hadron production, we demonstrate...
The Micro Vertex Detector (MVD) is the first downstream detector of the fixed-target CBM experiment at the future Facility for Antiproton and Ion Research (FAIR). It enables high-precision tracking of low-momentum particles in direct proximity of the target, e.g., the first out of four planar stations is placed only 8 cm downstream the interaction point. Thus, minimizing the material budget...
The Compressed Baryonic Matter (CBM) experiment will be installed at the Facility for Antiproton and Ion Research (FAIR). It aims to explore the phase structure of strongly interacting (QCD) matter at large net-baryon densities and moderate temperatures by means of heavy-ion collisions in the energy range $\sqrt{s_{NN}} = 2.9 - 4.9$ GeV. A key observable for the anticipated first order phase...
Dense QCD matter may exhibit crystalline phases. Their existence is reflected in a moat regime, where mesonic correlations feature spatial modulations. We study the realtime properties of pions at finite temperature and density in QCD in order to elucidate the nature of this regime. We show that the moat regime arises from particle-hole-like excitations near the Fermi surface. This gives rise...
Jets are collimated bunches of hadrons, and they serve as a useful tool for studying QCD. Jets are generated from the hard scattering processes of quarks and gluons in particle collisions, such as those at the Large Hadron Collider (LHC). These processes can be theoretically described by perturbative QCD (pQCD) and are well-modeled by Monte Carlo simulations such as PYTHIA and...
The nature of the QCD phase transition in the chiral limit presents a challenging problem for lattice QCD. However, its study provides constraints on the phase diagram at the physical point. In this work, we investigate how the order of the chiral phase transition depends on the number of massless quark flavors. To approach the lattice chiral limit, we map out the chiral critical surface that...
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...
The dual-radiator RICH (dRICH) detector of the ePIC experiment at the future Electron-Ion Collider (EIC) will make use of silicon photomultiplier (SiPM) sensors for the detection of the Cherenkov light emitted by particles crossing its radiators. The photodetector will cover $\sim$ 3 m$^{2}$ with 3$\times$3 mm$^{2}$ pixels, for a total of more than 300k readout channels. This will be the first...
The measurement of the magnetic field created in high-energy heavy-ion collisions is challenging, due to the fact that the magnetic field decays so drastically that in a thermalized quark-gluon plasma the field strength becomes rather weak. By incorporating the weak magnetic effect into the medium, and especially into the production formalism of dileptons from the quark-gluon plasma, the...
Dielectrons, emitted during the evolution of the hot and dense QCD medium created in relativistic heavy-ion collisions, offer an effective probe of the hot medium, as they are non-strongly interacting. The dielectron emission rate is proportional to the medium's electromagnetic spectral function. In the dielectron mass region $M_{ee} < 1$ GeV/$c^{2}$, the spectral function probes the in-medium...
We analyze the role played by thermal resonances in chiral and $U(1)_A$ transitions. The analysis will be carried out by studying several theoretical approaches based on effective theories. In particular, we will be interested in observables related to chiral symmetry restoration for which the lightest degrees of freedom provide the dominant effect. We will also discuss recent work on...
In this talk, we will present our extended studies on the bottom-up thermalization for a system composed by quarks, antiquarks and gluons. We will begin by performing parametric estimates for three distinct stages prior to hydrodynamization in the weak-coupling/high-energy limit, completing the analysis for pure gluon systems conducted by Baier, Mueller, Schiff, and Son. The predicted scaling...
We explore the thermodynamic geometry in the context of the chiral phase transition of Quantum Chromodynamics. In particular the thermodynamic curvature, $R$, provides insights into the system's fluctuations and critical behavior and thus can be considered as an alternative way to approach the study of critical phenomena. Building upon previous studies, we incorporate bosonic fluctuations...
It has been proposed to search for thermal and collective properties arising from parton-fragmentation processes by examining high jet charged-constituent multiplicities ($N_{j,ch}$) in proton-proton (pp) collisions [1]. Initial studies that tested this proposal using the PYTHIA 8 event generator with the Monash tune, incorporating multiparton interactions (MPI) and the MPI-based colour...
The spatiotemporal properties of the system created in heavy-ion collisions, including key information about its size and dynamics, can be studied via femtoscopy. In this talk, a differential study of the system size of Pb–Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.36 TeV with ALICE Run 3 data using correlations in momentum space of charged pion–pion pairs is presented.
In this study, the...
The study of the two-particle number correlation function, $R_{\rm 2}$, and the transverse momentum correlation function, $P_{\rm 2}$, has proven to be a crucial toolset to characterise the medium created during heavy-ion collisions. To complement the recent ALICE measurement in minimum-bias pp collisions, this contribution presents the study of multiplicity and transverse spherocity...
Relativistic hydrodynamics has been plagued with the problem of causality for a long time. While the proposal of MIS theories resulted in the restoration of causality, it introduced new degrees of freedom with no thermodynamic origin. Recent formulations of first-order hydrodynamics theories of BDNK type, where the hydrodynamic fields have generalized definitions, are both causal, and use only...
Higher-order moments of conserved charge fluctuations, such as net-charge, net-baryon, and net-strangeness, are sensitive experimental probes for investigating the critical fluctuations in relativistic heavy-ion collisions. We calculate the cumulants and correlation functions of proton, antiproton, and net-proton multiplicity distributions in Au + Au collisions at √sNN = 7.7 GeV using a...
Triangular flow in heavy-ion collisions, $v_{3}$, represents the third harmonic coefficient in the Fourier expansion of the azimuthal distribution of produced particles relative to the collision event plane. Since $v_{3}$ is sensitive to initial fluctuations of nucleons, it serves as a valuable tool for studying the fluctuations of the early initial conditions of the system and the...
Hadronisation is the complex process by which hadrons form from partons. Due to its non-perturbative nature, an exact theoretical description is unavailable, making phenomenological assumptions necessary. Currently, various hadronisation models are implemented in the Monte Carlo event generator PYTHIA 8.311. In this poster, we discuss tuning these hadronisation models using Professor [1] to...
The most recent measurements of femtoscopic correlations at NA61/SHINE, using intermediate collision systems, unravel that the shape of the particle emitting source exhibits non-Gaussian properties over the available energies. The measurements are based on alpha-stable symmetric Lévy sources, and we discuss the average pair transverse mass dependence of the source parameters. One of the...
The collision of a proton and a lead nucleus is asymmetric in nature, leading to an asymmetric rapidity distribution (more particles produced in the Pb-going side) of the produced particles at ultrarelativistic energies. We study multiplicity in such collision as a function of pseudorapidity, and centrality defined from the energy deposited in a calorimeter. In particular, we focus on the...
In this work, we study the localization properties of the eigenstates of non-Abelian SU(3) gauge theory both with and without dynamical quark flavors in a gauge invariant manner, using first-principles lattice gauge theory techniques. We use the eigenspectrum of a probe (overlap) Dirac operator to understand the properties of thermal gauge ensembles of 2+1 flavor QCD generated using domain...
The relative increase in the 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) collisions have shown features that are reminiscent of those observed in lead-lead (Pb--Pb) collisions, i.e. an increase in the...
We study the critical dynamics of a scalar field theory with $Z_2$ symmetry in the dynamic universality class of Model A in two and three spatial dimensions with classical-statistical lattice simulations. In particular, we measure the non-equilibrium behavior of the system under a quench protocol in which the symmetry-breaking external field is changed
at a constant rate through the critical...
We propose a novel set of flow observables designed to probe event-by-event fluctuations of conserved charges in relativistic high-energy collisions. We find that, in $\rm Pb\texttt{+}Pb$ collisions at the LHC $\sqrt{s_{NN}}=5.02$ TeV, our observables are sensitive to local fluctuations in baryon number (B), strangeness (S), and electric charge (Q), which in turn lead to measurable effects in...
Understanding the impact of nuclear structure in high-energy nuclear collisions is critical to advancing our knowledge of quark-gluon plasma (QGP) formation. In this study, we investigate the role of nuclear clustering, in particular the alpha-cluster structure in $\rm ^{16}O$, using anisotropic flow observations from $\rm ^{16}O+^{16}O$ collisions at RHIC energy. Through systematic...
Jet substructure measurements at the LHC produce precision tests of jet formation and fragmentation in vacuum as well as at the high temperatures and densities formed in heavy-ion collisions. Jets containing a heavy-flavor hadron drive these QCD measurements into a regime where parton mass and colour factors are critical, pushing the limits of theoretical calculations both in-vacuum and...
Recent CMS measurements of high-multiplicity jets have revealed intriguing structures in two-particle correlations within jets containing over 80 charged tracks, potentially indicating the presence of final-state interactions beyond those modeled in existing parton shower frameworks. We investigate two mechanisms of final-state interaction that may become significant when the phase-space...
The study of hadronic resonances provides valuable information about the final state interactions and the system evolution in ultra-relativistic nuclear collisions. Due to their short lifespan, comparable with the duration of the hadronic phase, resonances can be affected by the competing re-scattering and regeneration mechanisms. In particular, their decay daughters interact elastically with...
Momentum transport in a medium is characterized quantitatively by its shear and bulk viscosities. The shear viscous coefficient ($\eta$) governs the momentum transport transverse to the hydrodynamic flow while its bulk counterpart ($\zeta$) does the same along the flow. In the context of quark gluon plasma (QGP), both $\eta$ and $\zeta$ are very important transport coefficients, controlling...
We begin by using Hybrid Model calculations to reproduce experimental results published by ATLAS in 2023 on $R_{AA}$ for $R=1$ jets in Pb+Pb collisions. These jets are identified by first reconstructing anti-$k_t$ $R=0.2$ subjets and then re-clustering them. Following ATLAS, we investigate how $R_{AA}$ for these large-radius jets depends on the angle between the two subjets involved in the...
We explore the emergence of collective behavior in a weakly-coupled quark-gluon plasma using relativistic kinetic theory. To model the plasma formed in central high-energy nuclear collisions, we consider a system that expands boost-invariantly along the longitudinal (beam) direction and develops azimuthally symmetric transverse flow. Using the Boltzmann equation and a special set of moments of...