In non-central heavy-ion collisions, large orbital angular momentum and strong vorticity fields are produced and predicted to polarize quark spins. Unexpectedly large global spin alignment ($\rho_{00}$) values for ${\phi}$(1020) mesons have been reported in the first phase of the RHIC Beam Energy Scan (BES-I) in Au+Au collisions [1]. These values exceed conventional expectations based on...
One of the main physics goals of the Beam Energy Scan (BES) program at RHIC is to study the QCD phase diagram, especially around the phase transition between the quark-gluon plasma (QGP) and hadronic matter. BES Phase-I studied Au+Au collisions from center-of-mass energies ($\sqrt{s_{_{\rm{NN}}}} $) of 7.7 to 62.4 GeV. BES Phase-II extended these measurements in several important ways, one of...
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...
We formulate an efficient covariant method for interacting N-body systems with correct density-dependent potential and consistent mass-shell constraints. We implement it in the Monte-Carlo event generator JAM2 and calculate anisotropic flows for RHIC Beam Energy Scan (BES) energies.
Microscopic transport approaches such as Boltzmann-Uehling-Uhlenbeck (BUU) and Quantum Molecular Dynamics...
Based on a generalized Beth-Uhlenbeck approach to thermodynamics of QCD we explain why the abundances of hadrons produced in ultrarelativistic heavy-ion collisions are well described by the hadron resonance gas (HRG) model with a sudden chemical freeze-out at a well-defined hadronization temperature despite the fact that state of the art results of lattice QCD indicate a smooth chiral...
Bayesian inference in heavy-ion physics often produces varying estimates of model parameters when varying the physics model and/or the prior assumptions, reflecting a lack of accounting for theoretical uncertainties. Traditionally, a good model-to-data fit is seen as success, with inferred parameters assumed to reflect underlying physics. However, theories have limitations and extending a...
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...
We analyze the finite temperature potential of X(3872) in the Born-Oppenheimer approximation under the assumption that it is a tetraquark. At large number of colors, the potential is argued to consist in a real part plus a constant imaginary term. The former is calculated using as input at zero temperature lattice QCD determinations of the potential for hybrids. For its extension to finite...
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...
In small collision systems like O-O, the initial energy density profile and pressure gradients driving anisotropic flow are expected to exhibit greater fluctuations compared to larger systems such as Pb–Pb. This emphasizes the significance of initial nuclear geometry and raises questions about the applicability of hydrodynamic evolution in this regime. Investigating collective signals in these...
Anisotropic flow measurements in heavy-ion collisions are sensitive to the spatial distribution of the initial state, and QGP transport properties such as the shear viscosity to entropy density ratio $(\eta/s)$.
Hydrodynamic models successfully describe such flow measurements over a wide centrality range. However, the hydrodynamic description of anisotropic flow deviates from the data in...
The development of collective dynamics in collisions involving small atomic nuclei at RHIC and the LHC is still a hot research topic. In the first part of the talk [1] we explore the applicability of hydrodynamics in small collision systems, using viscous anisotropic hydrodynamics (VAH). VAH is a form of relativistic fluid dynamics specifically designed to handle the large pressure...
In high-energy hadron-hadron collisions at the LHC, Multiple Parton Interactions (MPI), where multiple hard-parton scatterings occur in a single collision, play a significant role. Among these, Double Parton Scattering (DPS) represents the simplest case, where two independent scatterings take place simultaneously. The DPS contribution to processes involving two final states, A and B, can be...
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...
Motivated by recent progress in spin hydrodynamics, we investigate the spin density matrix of baryons and vector mesons allowing for non-equilibrium between spin and vorticity.
We explain how the coalescence of partially polarized quarks, as well as the transfer of angular momentum from vorticity to the spin of the baryon generically create a partially coherent density matrix.
We argue that...
Anisotropic collective flow provides valuable information about the evolution of nuclear matter in the early stages of collisions and is one of the commonly used observables in high-energy heavy ion collisions. The first harmonic coefficient in the Fourier expansion of the
final-state azimuthal anisotropy, relative to the reaction plane, is referred to as directed flow, $v_1$.The $v_1$ slope...
The first harmonic coefficient of the Fourier expansion of the final-state momentum-space azimuthal distribution of produced particles is called directed flow ($v_{1}$). It describes the collective sideward motion of emitted particles. $v_{1}$ is sensitive to the equation of state of nuclear matter, making it a useful probe for studying the phase transition. Results from the RHIC Beam Energy...
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...
Bottomonium production is sensitive to both the structure of nucleons and
the interactions of b quarks with the nuclear media produced in heavy-ion collisions. The LHCb detector’s forward geometry allows for studying bottomonium production in a unique kinematic regime. Recent LHCb studies of bottomonium production will be presented, including multiplicity-dependent measurements sensitive to...
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...
The LHCb experiment’s forward acceptance offers a unique opportunity to study bulk physics in heavy-ion collisions. Properties of bulk particle production, such as the average transverse momentum of charged particles, are sensitive to both collective phenomena and the initial state of heavy-ion collisions. Bulk physics measurements in small collision systems can reveal the interplay between...
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....
Charmonium production in hadronic collisions is an important experimental observable that sheds light on the heavy quark interaction with the nuclear medium. While the bound quarkonium states undergo dissociation and recombination in PbPb collisions, in pPb collisions they can experience a combination of initial- and final-state effects such as shadowing and comover breakup. A full description...
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...
Anisotropic flow is one of the key signatures of the quark--gluon plasma (QGP) created in relativistic heavy-ion collisions at the LHC. This phenomenon is generally quantified by the different harmonics, $v_n$, of the Fourier expansion measured through the azimuthal distribution of final-state particles. In this poster contribution, we report on the first results of $v_n\{m\}$ measurements of...
This contribution comprehensively presents measurements of charged pions, kaons, and protons produced in Pb-Pb collisions at √sNN = 5.36 TeV using the ALICE detector at the Large Hadron Collider (LHC). Particle identification was achieved through a combination of the Time Projection Chamber (TPC) and the Time-of-Flight (TOF) detectors, allowing for a measurement that spans a broad...
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...
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...
Deep learning (DL) techniques have emerged as powerful tools for advancing our understanding of high-energy nuclear physics. We employ DL methods to probe two crucial phenomena: collective flow in small colliding systems and the chiral magnetic effect (CME) in heavy-ion collisions.
Collective flow is similar between small colliding systems ($p$ $+$ $p$ and $p$ $+$ A collisions) and large...
A recently formulated thermal model for hadron production in heavy-ion collisions in the few-GeV energy regime is combined with the idea that some part of protons and neutrons present in the original thermal system forms deuterons via the coalescence mechanism. Using realistic parametrizations of the freeze-out conditions, which reproduce well the spectra of protons and pions, we make...
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...
The Compressed Baryonic Matter (CBM) experiment is a fixed-target experiment currently under construction at FAIR in Darmstadt which will explore the QCD phase diagram at high net-baryon densities using heavy-ion beams in the kinetic energy range of 2-11 AGeV provided by the SIS100 accelerator complex. Dielectrons serve as versatile probes for properties of the hot and dense medium created in...
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...
Leading-order pQCD calculations have shown dileptons to be a promising signature of the preequilibrium in ultrarelativistic heavy-ion collisions. This work extends the analysis of dileptons as a probe of chemical equilibration to next-to-leading order accuracy. Since the system is far-from-equilibrium, we employ the real-time formalism of quantum field theory to perform this kind of...
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 $^{4}_{\Lambda}{\rm He}$...
This work focuses on the effects of rotation on the transport coefficients and observables of the QGP medium. Since the noncentral heavy ion collisions possess finite angular momentum with a finite range of angular velocity, the rotation gets incited in the produced medium. The rotation could significantly alter the transport coefficients and observables, such as the electrical conductivity,...
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 beam energy scan probes the QCD phase diagram from high temperatures, low densities (high energies) to low temperatures and high densities (low energies). At high energies the system is boost-invariant such that 2+1D simulations using hyperbolic coordinates can reasonably capture most of the dynamical behavior for symmetric collisions, but as one lowers the beam energies the Lorentz...
We employ a Relativistic Full Boltzmann Transport approach to investigate the emergence of universality in a wide range of collision systems, starting from a typical $pp$ setup and going up to $pA$ and $AA$ collisions. Our focus is concentrated on the attractor behaviour in the momentum moments of the distribution function and in the anisotropic flows $v_n$, with particular attention on the...
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...
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...
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...
The ultrarelativistic motion of charges in heavy-ion collisions is responsible for generating extreme electromagnetic fields, with magnetic fields of the order of $10^{18} \; G$ (for RHIC energies) [1]. However, the fields are very short-lived and their effects on the dynamics of the hot and dense matter produced in the collision are not well understood. In this work, we use a hybrid...
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...
The evolution of the strongly interacting medium formed in heavy-ion collison is modelled with multi-stage models. The models are driven by a large number of parameters that quantify the properties of the medium and the initial stage of the heavy-ion collision. The need to find model parameters which give the best description of the experimental data imposes a multidimensional optimization...
We investigate the dynamics of heavy quarks during the initial stages of relativistic nuclear collisions. The initial pre-equilibrium stage of heavy-ion collisions, commonly known as Glasma, evolves according to the classical Yang-Mills (CYM) equations. Heavy quarks are coupled to the evolving Glasma fields via relativistic kinetic theory. We compute the momentum broadening as well as 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...
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...
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...
The measurement of strangeness production is a key tool for understanding the hot, dense matter created in relativistic heavy-ion collisions. The production of strange hadrons is enhanced in heavy-ion collisions due to thermal gluon saturation, while it is suppressed in small systems due to canonical suppression, as supported by canonical models. Despite being one of the earliest signatures of...
We present a self-consistent method to describe a conformal
plasma composed of three quark flavors (particles + anti-particles) in the
presence of strong magnetic fields by means of kinetic-theory tools. Based
on a specific ansatz for the dissipative correction to the equilibrium
distribution function, we explicitly solve the Boltzmann equation in
relaxation-time approximation, including...
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...
Ida Storehaug, for the ALICE Collaboration
The $\text{B}^\pm$ meson is the most frequently produced beauty meson in proton-proton (pp) collisions at the LHC. Measuring its production cross-section is important for two reasons. First, it allows for testing of perturbative quantum chromodynamics calculations. Second, the $\text{B}^\pm$ meson cross-section measurement provides an essential...
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 $\sqrt{s_{NN}}=2.23$...
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...
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...
In this work, we discuss the impact of phase transitions on quark spin fluctuation and correlation. We propose a novel observable for quark-antiquark correlation that relates to vector meson spin alignment and $\Lambda-\bar\Lambda$ correlation. Using the NJL model, we qualitatively study the properties of quark-antiquark spin correlation. Our findings reveal a peak structure near the CEP,...
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...
Heavy-ion collisions in the energy regime of $\sqrt{s_\mathrm{NN}}=$ 2 - 20 GeV, are relevant for the study of dense baryonic matter and the hunt for the critical end point of QCD. In this energy regime the well established hybrids of single-fluid hydrodynamics coupled to transport afterburners are reaching their limitation due to long interpenetration times and an intricate time...
Accurate modeling and understanding of quarkonium production in AA collisions requires a formalism that preserves the quantum properties of a microscopic $Q\bar{Q}$ systems while treating the interaction of such pairs with the QGP. The open quantum system approach has recently emerged as one of the most fruitful schemes to meet such requirements. However, the quantum master equations obtained...
Jets originating from hard-scattered partons from the early stages of heavy-ion collisions travel through the Quark Gluon Plasma (QGP) and are modified or quenched relative to a p+p collision baseline. Moments of the jet’s transverse momentum, $p_{\text{T}}$, profile in the $ \eta - \varphi $ plane relative to the jet axis, called generalized jet angularities $\lambda_\alpha^\kappa$, are an...
We introduce generalized tensor forms of thermodynamic relations used in relativistic perfect spin hydrodynamics. They are valid in the cases of Boltzmann and Fermi-Dirac statistics and allow for consistent treatment of spin degrees of freedom, also for large values of the spin polarization tensor $\omega_{\mu \nu}$ and for spin tensors $S^{\lambda, \mu \nu}$ of a form motivated by kinetic...
The Compressed Baryonic Matter (CBM) experiment is an upcoming fixed target experiment being built at the Facility for Anti-proton and Ion Research (FAIR).
The CBM experiment is designed to characterize the QCD medium at high net baryon densities and moderate temperatures.
Di-electrons interact electromagnetically and are unaffected by strong medium effects.
Hence, they are used as a...
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...
Developments in phenomenology, such as model variations, advances in color reconnection models, and the pursuit of precision tuning, alongside the growing demand for faster simulations to match the increasing luminosity at the LHC, have driven significant progress in string model-based hadronization simulations in PYTHIA. In this talk, I will present an overview of recent efforts to integrate...
The differences in hadron chemistry observed at e+e- machines versus hadron
colliders may indicate that the mechanisms by which partons evolve into visible matter are not universal. In particular, the presence of many other quarks produced in the underlying event may affect the hadronization process. With full particle ID, precision vertexing, and a high rate DAQ, the LHCb experiment is...
We study the impact of the glasma initial pre-equilibrium stage of heavy-ion collisions on heavy quarks spectra and correlations. Our main finding is that the effect of glasma on the nuclear modification factor $R_{AA}$ for the heavy quark transverse momentum spectrum is moderate, while $c\overline{c}$ angular correlations are strongly affected by the glasma [1]. Such correlations are relevant...
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...
Measurements of heavy baryon production in pp, pA and AA collisions from RHIC to top LHC energies have recently attracted more and more attention, currently representing a challenge for the heavy-quark hadronization theoretical understanding.
An hybrid coalescence plus fragmentation approach has been able to correctly predict the large baryon over meson ratio $\Lambda_c/D^0\sim O(1)$...
We evaluate the heavy quark momentum diffusion coefficients in a hot magnetized medium for the most general scenario of any arbitrary values of the external magnetic field. We choose to work with the systematic way of incorporating the effect of the magnetic field, by using the effective gluon and quark propagators, generalized for a hot and magnetized medium. To get gauge independent analytic...
To date, holographic calculations have provided separate descriptions for the rates of energy loss for either ultrarelativistic massless quarks and gluons or infinitely massive quarks in strongly coupled N=4 SYM plasma. We present a unified description of heavy quark energy loss by combining the limits of zero mass $M \to 0$ and infinite mass $M \rightarrow \infty$ in such a way that ensures...
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...
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...
To understand the surprising accuracy of hydrodynamic predictions for the quark-gluon plasma in heavy-ion collisions, many have turned to studying attractor solutions in the underlying kinetic theory. Aside from experimentally motivated assumptions such as Bjorken flow, ignoring the presence of spatial gradients has often been helpful to facilitate theoretical calculations. We challenge this...
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...
The observation of hyperon polarization along beam direction ($P_z$) in nucleus-nucleus collisions has opened a new way to study the complex vortical structures of the QGP. With the high-statistics data collected by the CMS experiment, we present the first $P_z$ results for $\Lambda$ and $\bar{\Lambda}$ particles in pPb collision at $\sqrt{s_{NN}}= 8.16$ TeV over a wide transverse momentum...
After formulating the angular momentum conservation in a covariant form, we consider the equations of spin hydrodynamics in the background of an uncharged fluid in global equilibrium with a non-vanishing thermal vorticity.
Assuming that the spin degrees of freedom are not in equilibrium, we derive relaxation-type equations for the components of the spin potential.
These equations generalize...
In this work, we analyze the impact of open-heavy-flavor-production data in proton-lead collisions on the nCTEQ nuclear PDFs. For the theoretical predictions of this process, we use an existing next-to-leading-order calculation in a general-mass variable-flavor-number scheme (GM-VFNS), which, as a pQCD alternative, we compare to the data-driven approach for open heavy-flavor production used in...
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....
Motivated by hydrodynamics of small systems we investigate the conceptual problem of how to match hydrodynamics, a classical deterministic theory, to the 3D structure of the nucleon, information encoded in deeply quantum stuctures such as GPDs and TMDs.
We show that concepts from the Wounded nucleon model can nevertheless be applied to such objects provided one assumes ``instant...
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...
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...
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...
We perform a phenomenological study of chemical equilibration using viscous hydrodynamic evolution with an equation of state that parameterize gluon-quark chemical equilibrium through fugacities for each quark flavor. We initialize the QCD medium in a gluon-dominated state and account dynamically for chemical equilibration during the hydrodynamic phase through time-dependent fugacities. We...
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...
Recent measurements of light-flavour particle production in small collision systems (pp and p-Pb) at LHC energies revealed features such as collective behaviour and strangeness enhancement, typically seen in nucleus-nucleus collisions. These effects seem to be correlated to charged-particle multiplicity, regardless of the collision system. For this reason, it is important to investigate small...
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...
Unlike the earlier paradigm in physics, recent advancements in machine learning focus on uncovering physical law through data-driven approaches. In this talk, we leverage well-trained feedback neural networks (FNNs), combined with phenomenological models and reliable nuclear mass data from AME2020 and AME2016, to predict atomic masses with exceptional accuracy and extrapolation capabilities,...
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...
Measurements of charm-hadron production provide a fundamental test to validate the perturbative quantum chromodynamics (pQCD) calculation.
However, in recent years, an enhanced production of charm baryons relative to mesons was observed compared to $\mathrm{e}^{+}\mathrm{e}^{-}$ collisions, challenging the assumption of independent fragmentation adopted in pQCD calculations via the...
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 $J/\psi$ meson, consisting of a charm quark and its antiquark, serves as an exceptional testing ground of Quantum Chromodynamics (QCD). However, our understanding of its underlying production mechanism remains incomplete. One of the principal challenges lies in experimentally disentangling perturbative from non-perturbative process contributions. The recently proposed $J/\psi$-energy...
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...
The production of hadrons containing charm or beauty quarks in proton-proton (pp) collisions mainly happens via initial hard-scattering processes and provides an important test for quantum chromodynamics calculations. In fact, due to their large masses, heavy quarks can only be produced in processes with high-momentum transfer and hence can be ascribed by perturbative QCD calculations. These...
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...
Significant global hyperon polarization has been observed in non-central heavy ion collisions providing evidence of the vorticity of QGP. This effect can serve as a new probe in exploring fluid properties of strongly interacting matter. We present results of $\Lambda$ and $\bar{\Lambda}$ global polarization in Au+Au collisions at $\sqrt{s_{NN}}$=7.7, 9.2, 11.5, 14.6 and 17.3 GeV from RHIC...
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...
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...
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 study of quarkonium production in $p$+$p$ collisions is of great interest in understanding the relative importance of mechanisms that contribute to its formation, which is an outstanding question. The investigation of the soft and hard processes involved in quarkonium formation is key in constraining the theoretical models and helping to differentiate between them.
This poster presents...
Measurements of the anomalous magnetic moment of leptons provide stringent tests of the Standard Model and potential hints of physics beyond the Standard Model. These measurements for electrons and muons are among the most precisely measured quantities in physics. However, due to the short lifetime of the tau lepton, it is impossible to measure its anomalous magnetic moment through traditional...
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...
Dileptons, being electromagnetically decoupled from the strongly interacting medium, are key probes of the thermal and chemical evolution of the Quark-Gluon Plasma (QGP) and the hadronic matter. In the intermediate mass range ($m_\phi < m_{ee} < m_{J/\psi}$), they primarily originate from the thermal radiation of the QGP and semi-leptonic decays of heavy flavor mesons. Disentangling these...
The second harmonic cosine and sine modulations of the local spin polarization of $\Lambda$($\bar{\Lambda}$) hyperons out-of-plane ($P_{y}$) and in-plane ($P_{z}$), denoted as $P_{2y}$ and $P_{2z}$, respectively, are newly proposed observables for probing spin Hall effect (SHE) in high-density baryonic region. $P_{2y}$ and $P_{2z}$ are measured in Au+Au collisions at $\sqrt{s_{NN}} = $ 7.7,...
Femtoscopy is a powerful technique for probing both the emission source and the interaction potential between particle pairs. The key observable in femtoscopy is the two-particle correlation function, which provides crucial insights into the space-time dynamics of the emitting source as well as final-state interaction effects. Among the less explored interactions is the hyperon-hyperon (YY)...
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...
The observation of hyperon global polarization along the system's angular momentum has revealed the existence of large vorticities in the medium created by heavy-ion collisions.
Using the high-statistics data collected by the STAR experiment during the RHIC BES-II program with upgraded detector systems, we present the global polarization measurements for $\Xi^{\pm}$ and $\Omega^{\pm}$...
Elliptic ($v_2$) and triangular ($v_3$) flow in the forward and backward rapidity regions, are sensitive to the equation of state of hot and dense nuclear matter as well as the initial conditions in heavy-ion collisions. According to hydrodynamic models, the rapidity dependence of $v_2$ and $v_3$ has a strong constraining power on the temperature dependence of specific shear viscosity...
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...
Measurements of weak bosons, W$^{\pm}$ and Z$^{0}$, are powerful tools to study quantum chromodynamics (QCD).
Due to their large masses, they are predominantly produced via quark-antiquark annihilation in the early stage of pp and heavy-ion collisions.
Therefore, their production can be described by the perturbative QCD (pQCD) and is sensitive to the parton distribution function in nucleon...
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...
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...
Recent measurements of the self-normalised yield as a function of charged-particle multiplicity in pp collisions at $\sqrt{s}=$13 TeV showed a faster than linear increase for both light-flavour and heavy-flavour hadrons, which is found to be more pronounced for high
$p_{\rm{T}}$ particles. Models accounting for multiparton interactions (MPI) and color-reconnection (CR) effects describe the...
The study of multiplicity-dependent yields ratio of light-flavour particles like kaons, and protons to pions offers valuable insights into mechanisms hadron production. The $K/\pi$ and $p/\pi$ ratios are crucial in understanding how particle production scales with multiplicity across different systems. In particular, these ratios reveal whether strange and baryonic particle production...
Bayesian statistical analysis is nowadays a well-established method for performing global fits of QCD matter properties and initial conditions to experimental data from ultrarelativistic heavy ion collisions. However, even when surrogate models such as Gaussian process emulators are used to reduce the number of simulations, the computational costs can still remain prohibitively large for...
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...
The way a relativistic system approaches fluid dynamical behavior can be understood physically through the signals that will contribute to its linear response to perturbations. What these signals are is captured in the analytic structure of the retarded correlation function. The non-analyticities can be grouped into three types based on their dimension in the complex frequency plane. Using...
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...
Hybrid numerical models based on relativistic hydrodynamics have successfully described key aspects of the evolution of the hot and dense matter produced in ultra-relativistic heavy-ion collision experiments. At the end of the hydrodynamical stage, the continuous fluid degrees of freedom are translated to the discrete components of a hadron resonance gas described by kinetic theory. This...
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...
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...
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...
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...
Measurements of light hadron production play an important role in understanding final state effects in ultrarelativistic nucleus-nucleus collisions. These include the implications of collective flow in both large and small systems as well as the impact of hadronization by recombination on baryon and strangeness enhancement. Studies of the system size dependence of various observables also...
Heavy-ion collisions at energies of a few GeV involve significant baryon stopping in the fireball region, leading to the formation of a baryon-dominated system. This system is characterized by large values of the baryo-chemical potential ($\mu_B$) at chemical freeze-out, as determined through statistical-chemical analysis of hadron yields. However, at these lower energies, the freeze-out...
The High Acceptance Di-Electron Spectrometer (HADES) [1] installed at the GSI institute in Darmstadt registers products of heavy ion collisions at energies of a few GeV per nucleon. The nuclear matter produced in such collisions reaches extreme densities and temperatures [2, 3, 4], comparable to those found in neutron stars, especially during their mergers [5]. By...
The chiral magnetic effect (CME) is a novel transport phenomenon that offers the unique opportunity for experimental observation of transitions between different vacuum topological sectors of QCD. A measurement of the CME signal also helps probe the dynamical magnetic field as well as chiral symmetry restoration, which are key ingredients of the phenomenon. Significant efforts have been made...
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...
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...
Heavy quark energy loss in a strongly coupled $N=4SU(N_c)$ has been studied using AdS/CFT correspondence, which shows hydrodynamic excitations to be the primary modes. Similar results are lacking for strongly coupled QCD plasma due to absence of dual description. Motivated by the AdS/CFT result, we construct an effective field theory of heavy quark in a hydrodynamic medium which aims to...
Heavy-ion collisions in the few-GeV energy range allow the creation of strongly interacting matter under extreme net-baryon densities, conditions which are comparable to the ones in neutron star mergers. The precise investigation of the Equation-of-State (EoS) of this kind of matter is therefore of high relevance for the understanding of neutron stars.
In this contribution, we present new...
In heavy-ion collisions, the elliptic flow ($v_{2}$) represents the second harmonic coefficient in the Fourier expansion of the azimuthal distribution relative to the reaction plane. It serves as a sensitive indicator of the interaction strength among the system’s constituents and offers a valuable means to explore its degrees of freedom.
In this poster, we will present $v_{2}$...
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 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...
Exploiting the first measurements of the same ion species in O+O collisons at RHIC and LHC, we propose an experimentally acessible observable to distinguish whether collective behavior builds up through a hydrodynamic expansion of a strongly interacting QGP or through few rescatterings in a non-equilibrated dilute medium. Our procedure allows to disentangle the effects of the initial state...
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...
Quarkonia are golden probes for studying the properties of the medium produced in heavy ion collisions. Various measurements for different quarkonium species at RHIC and the LHC indicate that their suppression levels follow the ordering of their binding energies. Additionally, recombination effects are substantial in nucleus-nucleus collisions, particularly charmonium states. However,...
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...
Self similar evolution in time, also known as a nonthermal fixed point, is one of the stages of thermalization in QCD under the assumption of very weak coupling. This arises in models of ultra-relativistic nuclear collisions and cold atomic gases, for the latter this has been experimentally realized. Nonthermal fixed points are characterized by a universal scaling function and power law...
In recent years, analyses using RHIC-BES data have been actively conducted to explore the high baryon number density region in the QCD phase diagram. Meanwhile, even in high-energy collisions, such as RHIC and LHC energies, the presence of high baryon number density matter in the forward rapidity region has been suggested [1]. This implies that, in addition to the analysis of BES data, a...
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 forward geometry and precision instrumentation of the LHCb spec-
trometer provides unique insights into the production of heavy quarks at the LHC. Heavy quark production in pPb collisions are sensitive to the modification of nuclear parton distribution functions, energy loss in the nucleus, and the hadronization process, among other effects. In this talk, precision measurements of open...
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...
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...
Investigating collective behavior due to the formation of a fluid-like medium in small collision systems has been a significant focus in the field. A tell-tale signature of this would be the medium's response to the initial state in small collision systems, as predicted by fluid-dynamic models.
Recent RHIC studies of small systems have shown a hierarchy of elliptic anisotropy coefficients...
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...
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,...
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...
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 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 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...
Heavy-flavor jets produced in high-energy collisions are a unique probe to test the pertubative quantum chromodynamics (pQCD), and are one of the major science portfolios for the new sPHENIX experiment. Searching for charm and bottom jets is one of most challenging measurements in collider experiments due to their rare production rate and extensive backgrounds. The sPHENIX experiment has...
sPHENIX is the first new collider detector experiment for heavy-ion physics since the switch on of the LHC and was successfully commissioned during 2023 and 2024. A major feature of sPHENIX is the use of a tracking system capable of streaming readout, enabling the collection of very large, unbiased p+p datasets previously not available at RHIC. Using this ability, sPHENIX recorded over 100...
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 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...
We use a potential model to investigate the phenomenology of quarkonium in a thermal rotating medium, where vorticity and spin density are not necessarily in equilibrium. We find that the quarkonium spin density matrix, as well as the binding energy and melting temperature, are sensitive to both the vorticity and the lack of equilibrium between vorticity and spin. This means that quarkonium...
The global spin alignment of $\phi$ meson has been observed by the STAR collaboration in Au+Au collisions at RHIC. However, the measured positive deviation from 1/3 of the spin alignment is orders of magnitude larger than contributions of traditional mechanisms like vorticity or magnetic fields. We proposed that the anisotropy of local strong field fluctuation in meson's rest frame is a new...
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...
Stochastic hydrodynamics provides a dynamical framework for the evolution of fluctuations in heavy-ion collisions. Due to the small volume of the system, thermal fluctuations can become sizeable and probe the equation of state of the system, being particularly sensitive to a possible QCD critical endpoint.
Our present numerical setup can simulate stochastic non-relativistic hydrodynamics in a...
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...
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...
Multi parton interaction is an essential part of high energy heavy ion collision. In fact, the contribution of double parton scattering (DPS) in nuclear collision in the total charm cross section is significant in LHC energies. By studying double charm correlation, one can extract information about the contribution of DPS production. Also, the correlation from single scattering is used to...
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...
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...
The multi-particle cumulants method is a powerful tool for revealing long-range collectivity in small and large colliding systems. The three-particle asymmetric cumulant $ac_{2} \left \{ 3 \right \}$, four-particle symmetric cumulant $sc_{2,3} \left \{4\right\}$, $sc_{2,4} \left \{4\right\}$, and higher order six-particle symmetric cumulant $sc_{2,3,4}\left \{6\right\}$, from the transverse...
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...
Despite the success of hydrodynamic models in describing relativistic heavy-ion collisions, questions persist about their regime of validity. Non-linear causality conditions provide a clear criterion for assessing the applicability of models. If the evolution of a system violates causality, it cannot reliably represent the underlying relativistic theory. It is now known that state-of-the-art...
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...
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 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...
The virtual photons emitted during the early stages of relativistic heavy-ion collisions can escape the strongly interacting matter and be measured. This study shows that their polarization can reveal much about the nature of their production mechanism. We present the results of a comprehensive investigation of dilepton polarization generated by a quark-gluon plasma produced in Pb+Pb...
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 spectral functions of chiral partners should become degenerate when the QCD chiral symmetry is restored. The axial-vector spectra are experimentally more challenging to construct than those of vector mesons that directly couple to virtual photons and then to dileptons. Chiral mixing of the vector with axial-vector mesons is thus a key phenomenon to probe in-medium modifications of vector...
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...
It has recently been realized that in the ultra-central heavy-ion collisions, mean transverse momentum of hadrons contains the information of the fundamental thermodynamic properties of quark-gluon plasma (QGP). In particular, in nucleus-nucleus collisions the linear correlation between the mean transverse momentum and the charged multiplicity is attributed to the QCD speed of sound, which...
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...
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...
Azimuthal anisotropy is by now a standard observation in relativistic heavy-ion collisions, believed to primarily result from hydrodynamic expansion of the created hot and dense quark-gluon plasma (QGP). Ubiquitous observations of azimuthal anisotropy have also been made in small-system (proton-proton, proton-nucleus, and deuteron/$^{3}$He-nucleus) collisions. These observations, while...
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...
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...
Recent measurements of hadron production have revealed a non-universal behaviour in the fragmentation of partons into baryons in hadronic collisions compared to baselines in $\rm{e}^{+}\rm{e}^{-}$ and $\rm{ep}$ collisions. Exploration of this phenomenon is most controlled in the heavy-flavour sector, where the large mass of charm or beauty quarks allows us to experimentally relate a...
We derive expressions for the vector and tensor components of the spin polarization of massive vector bosons at local thermodynamic equilibrium, considering second-order spacetime gradients of thermodynamic fields—temperature, chemical potential, and flow velocity—in a relativistic fluid. A set of Feynman rules is developed to compute the Wigner function and matrix-valued spin-dependent...
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...
In most fields of science, visualizations help to understand concepts and to identify potential issues. For these reasons, animations of relativistic heavy-ion collisions provide interesting visual insights into the simulation software used as well as the time evolution of the collisions. In our work, we produce animations for collisions at several beam energies below 200 GeV for different...
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...
