Previous ALICE studies have shown a stronger than linear relative increase of the inclusive J/ψ production at mid-rapidity as a function of the mid-rapidity charged-particle multiplicity in proton-proton collisions. Studies on Monte Carlo simulations with PYTHIA 8 attributed this behavior to
autocorrelation effects. In this regard, interesting results were obtained studying the correlation...
In relativistic heavy-ion collisions, heavy quarks (charm and beauty) are predominantly produced in the early stage of the collisions via hard partonic scattering processes. Therefore, they experience the full evolution of hot and dense QCD matter in which quarks and gluons are de-confined (Quark-Gluon Plasma, QGP) created by such collisions, and can be an effective probe to study the QGP...
The high collision energies available at the LHC allow for an abundant production of heavy quarks (charm and beauty), which are sensitive probes for investigating the properties of the Quark-Gluon Plasma (QGP) formed in high-energy heavy-ion collisions. Due to their large masses, they are produced in initial hard parton scattering processes on a timescale shorter than the QGP formation time...
The NA61/SHINE hadron physics program focuses on a search for the critical point and on studies of the properties of the onset of deconfinement in strongly interacting matter. For this purpose the phase diagram is scanned by changing the collision energy (from 13A to 150/158A GeV/c) and the size of the colliding system (from p+p to Pb+Pb).
The main topic of this talk are preliminary results...
Recent experimental and theoretical obsevations suggest that production of (multi-)strange hadrons and charged hadrons in (non-)deformed nuclei is a complex physical process. The properties of charged hadrons produced in deformed nucleus collisions at RHIC and LHC energies contradict many of the theoretical models result including two-component Monte Carlo Glauber model. Unlike light hadrons,...
We report the first measurement of the Ξ(1820) baryon at LHC energies by reconstructing its decay to Λ-Κ in pp collisions at 13 TeV. Recent lattice calculations on parity doubling indicate that the masses of negative-parity particles, such as Ξ(1820), may decrease at the critical temperature, while the masses of positive-parity partners, i.e. the Ξ(1530), do not. Furthermore, the lifetime of...
One of the important goals of heavy-ion collision experiments is to test the predictions of Quantum Chromodynamics(QCD). One such QCD prediction is the formation of Quark-Gluon Plasma(QGP) in the heavy-ion collision experiments. Quarkonia suppression has been suggested as a sign of formation of QGP in heavy ion collision, where it could exist as a transient state. We have developed a model to...
It is understood that multiplicity fluctuations serve as one of the important observables for the study of the critical endpoint in the beam energy scan program of RHIC.
As a matter of fact, the problem is rather subtle, and many different factors may potentially affect the observable in question.
In this work, we take into consideration the thermal fluctuations, resonance decay, as well...
The Multi-Purpose Detector (MPD) is being constructed to study the properties of extremely dense nuclear matter formed in relativistic nucleus-nucleus collisions at NICA energies. The yields of strange and charmed particles are the important observables sensitive to critical phenomena in phase transitions of the QGP-matter at high net-baryon density. Highly efficient registration of such...
Correlated dielectron pairs are a very promising probe to study the quark-gluon plasma, a deconfined state of quarks and gluons predicted by lattice quantum chromodynamics calculations in ultra-relativistic heavy-ion collisions. Electrons reach the detector without significant final state interactions. In addition, the low-mass dielectron spectrum comes from various sources, i.e. Dalitz and...
We present an object-oriented software framework for performing the anisotropic flow analysis in collisions of ions and hadrons. The framework operates on flow Q-vectors and provides an abstraction layer for the analysis of two and multi-particle correlation functions. Its modular design and flexible interface allows to use it as an external software package, which fits the scope of any...
We consider causal higher order theories of relativistic viscous hydrodynamics in the case of one-dimensional boost-invariant expansion and study the associated dynamical attractor. We obtain the evolution equations for inverse Reynolds number as a function of inverse Knudsen number. The solutions of these equations exhibit attractor behavior which we analyze in the context of Lyapunov...
Recently anomaly related transports have attracted lot of interests in various fields. Ranged from low energy physics and in condensed matter up to high energy physics and in heavy ion collisions, physicists are interested to study the effects of microscopic anomaly over the macroscopic scales. Historically this stream is initiated by the work of Vilenkin in 1979 [ A.~Vilenkin, Phys. Rev. D ...
We use several methods to study the case of chiral anomaly with a non-relativistic dispersion relation $H=\frac{p^2}{2m}+\lambda\sigma\cdot p$, which might be useful in special condensed matter state. where $H$ means halmitonian.$\lambda$ is just a constant coeffecient.
we will show the results with different explanations in each methods. For example, the anomaly disappears for the lack of...
Flow correlations and fluctuations are sensitive probes to the initial geometry and the quark-gluon plasma (QGP) in relativistic heavy ion collisions. Model comparisons are essential to decipher the properties of the QGP. In this talk, we study the correlations between flow harmonics $v_2$, $v_3$, and $v_4$ over a wide centrality range with two-particle correlations in PbPb collisions at...
The hadronic interaction cross section for (multi)strange hadrons are expected to be small. Hence, the study of azimuthal anisotropy of (multi)strange hadrons allows one to access the collective properties of early stages in heavy-ion collisions. The STAR experiment recently recorded high statistics data for Au+Au collisions at a new centre-of-mass energies ($\sqrt{s_{NN}}$) of 54.4 GeV...
Two-particle angular correlations are used to investigate properties of the Quark-Gluon Plasma (QGP) formed in high-energy heavy-ion collisions. They are sensitive to different effects of the evolution of the collision, such as collective effects, initial conditions and jet properties.
In small systems (such as pp or p--A collisions), an unexpected double-ridge structure has been observed...
The Chiral Magnetic Effect (CME) manifests itself via a separation of electric charge along the direction of the magnetic field, produced by spectator protons in heavy-ion collisions. The experimental searches for the CME, based on the charge-dependent angular correlations [1] have, however, remained inconclusive till date, because the observed features of charge separation in data are also...
We present new results for fluctuations of the baryon number for QCD with
Nf=2+1 quark flavours at non-zero temperature and chemical potential [1].
These are extracted from a framework based on a combination of lattice QCD
and Dyson-Schwinger equations. In previous works ([2], see [3] for a review)
we found a critical end point in the region ($T^c,\mu_B^c$)=(120,500) MeV.
We discuss...
sPHENIX is a planned upgrade at RHIC designed to quantify the properties of quark-gluon plasma created in relativistic heavy ions collisions with a particular focuses on the measurements of jets and upsilon states. A crucial component to the sPHENIX detector design for jet measurements is the hadronic calorimeter (HCal) which is located outside of the solenoid magnet and composed of...
Femtoscopic measurements can be leveraged to gain insight into the expansion dynamics of the hot and dense medium created in heavy-ion collisions. This poster presentation will report and discuss excitation functions for shape-selected two-pion HBT radii ($R_{out}$, $R_{side}$ and $R_{long}$) measured for a a broad range of collision centrality and average pair transverse momentum ($k_{T}$)...
Recent ALICE results have demonstrated that femtoscopic measurements in pp and p-Pb collisions provide an unprecedented opportunity to study the short range part of the strong interaction.
Femtoscopy is a technique to extract information on the emission source and interaction potential from correlations between particles with low relative momentum. In this talk we will use femtoscopy to...
The study of the charm and bottom interacting with the QGP strongly relies on the precise measurement of their yields in p+p collisions, since the theoretical calculations of the yields have large uncertainties. The PHENIX collaboration has measured the semi-leptonic decay yields of charm and bottom hadrons and the non-prompt $J/\psi$ yield from B meson decays in 200 GeV $p$+$p$ collisions,...
We compute for the first time the suppression of bottomonia in a strongly coupled QGP and compare the results to those from a weakly coupled QGP and to data. Using imaginary time techniques we numerically determine the real and imaginary parts of the binding energy of $\Upsilon$(1S) in (complex) potentials derived from AdS/CFT and from pQCD. We confirm the strong coupling binding energies by...
Bottomonia are produced mostly in the initial stage of a heavy ion collision. Once created, any subsequent interaction with the medium can as a first approximation be dealt with as leading to dissociation. In that picture, the bottomonia surviving until the final state are those that escaped any interaction with the medium.
We compute the anisotropic flow of bottomonia arising from their...
Bottomonium, a bound state of a bottom quark and its antiquark, is an excellent probe of the hot and dense medium created in heavy-ion collisions at LHC. The ATLAS collaboration collected the large datasets of $pp$ and Pb+Pb collisions in 2017 and 2018 corresponding to integrated luminosities of 242 pb$^{-1}$ and 1.39 nb$^{-1}$ respectively, at a centre-of-mass energy per nucleon pair of 5.02...
In the soft and collinear limit, the choice of evolution scale in a parton shower algorithm is ambiguous and several options have been implemented in existing Monte Carlo event generators for proton-proton collisions. However, the resulting space-time evolution could result in subtle differences depending on the particular choice. In this work we quantify measurable consequences of the choice...
We examine the relativistic perfect fluid limit, defined as the fastest possible local equilibration,
in a medium with polarizeability, defined as a non-zero local equilibrium partition of angular
momentum into spin and vorticity. We show that the Lagrangian approach is best suited to
analyzing this situation, as it can be used to efficiently avoid issues such as the breakdown...
Bottom and charm production is a powerful tool to investigate the properties of
quark gluon plasma created in high energy heavy ion collisions. Heavy flavor production is calculable by perturbative QCD because of their large mass.
Once produced, they traverse the QGP and suffer the hot medium effects such as
energy losses. The collisional and radiative mechanisms play an important role of...
Event-by-event fluctuation of conserved quantities such as net baryon, net strangeness or net charge is considered to be a powerful tool to find the critical point (CP) on the Quantum Chromodynamics (QCD) phase diagram. To map out the QCD phase diagram, the Beam Energy Scan I (BES-I) program has been carried out at RHIC and non-monotonic behavior of the 4th-order net-proton cumulants was found...
The Compressed Baryonic Matter (CBM) experiment at the FAIR facility aims to explore the QCD phase diagram at very high baryon densities, where a first order phase transition from hadronic to partonic matter as well as a chiral phase transition is expected to occur.
The Silicon Tracking System is the central detector for momentum measurement and charged-particle identification. It is designed...
The Compressed Baryonic Matter (CBM) experiment is a fixed-target heavy-ion physics experiment at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. The CBM physics program aims at exploring the QCD phase diagram at very high baryon densities. For high-statistics measurements of rare probes, CBM is designed to cope with very high interaction rates up to 10 MHz. To...
One of the novel anomalous chiral effects, the chiral magnetic wave (CMW), has been experimentally searched by using the charge-dependent anisotropic flow in recent years. The observed linear dependence between the charge asymmetry and the flow of the positively and negatively charged hadrons, however, still remains inconclusive owing to the existence of background effects such as local charge...
In this poster, we will present measurements of event-by-event charge separation in Au+Au collisions at $\sqrt{{\it{s}}_{NN}} = 200$ GeV using Sliding Dumbbell Method (SDM). The charge dependent three-particle correlator ($\gamma = \langle cos(\phi_{a} + \phi_{b} - 2.{\Psi}_{RP}) \rangle$) which is the observable for Chiral Magnetic Effect (CME) [1] is investigated for each centrality...
Resonances are useful tools to study the properties of the hadronic medium produced in high energy heavy-ion collisions, due to their short lifetime. In particular, the baryonic resonance $\Lambda(1520)$ is important because of its lifetime ($\tau \sim$ 12.6 fm/$\it c$), which lies in between the lifetimes of $ K^*$ and $\phi$ resonances.
Its study will indicate the dominance of...
Hadronic resonances have been shown to be good probes to investigate the late-stage evolution of ultra-relativistic heavy-ion collisions. Their lifetimes are comparable with the time scale of the fireball generated in these collisions. Therefore they are sensitive to the competing re-scattering and regeneration effects occurring in the hadronic phase, which modify particle momentum...
Strangeness enhancement has been observed for several multi-strange hadrons in proton-proton (pp) collisions with increasing charged-particle multiplicity and is in remarkable agreement with measurements in p-Pb collisions. The yields of resonances with short lifetimes are sensitive to regeneration and re-scattering processes in the hadronic phase between chemical and kinetic freeze out. It is...
The ALICE experiment at the LHC is designed to investigate the properties of the Quark-Gluon Plasma by studying high-energy pp, p--Pb, Pb--Pb and Xe--Xe collisions. Medium effects like parton energy loss can be examined by measuring the production of charged particles and their nuclear modification at high transverse momentum ($\textit{p}_{\text{T}}$).
In this poster, we report on...
Heavy quarks (charm and beauty) are an effective tool to study the properties of the Quark-Gluon Plasma (QGP) formed in heavy-ion collisions at the LHC. Due to their large mass, they are produced during the early stages of the collisions in hard-scattering processes, on a time interval shorter than the QGP formation time. Thus, they experience the whole evolution of the system. The...
Charm quarks are effective probes used for the investigation of the Quark-Gluon Plasma (QGP) created in high-energy heavy-ion collisions. They are produced in hard scattering processes on a timescale shorter than the QGP formation time and experience the whole system evolution.
The measurement of charm-baryon production, and in particular the baryon-to-meson ratios, provides unique...
We present LHCb results on charmonia production in proton-lead collisions, using the data collected in 2016 at sqrt(s_NN) = 8.16 TeV nucleon-nucleon centre-of-mass energy, in the forward region (pseudorapidity between 2 and 5), covering forward (pPb configuration) and backward (Pbp configuration) rapidities. Measurements include prompt and from-b-decay components which are disentangled. The...
We redevelop the chiral kinetic theory (CKT) by exploiting the effective field theory method and find some disagreements at higher order of ($1/\mu$) from the earlier results. However, these disagreements are the same which have been pointed out by the off-shell effective theory formalism after identifying a cut-off. We address the discrepancies and by using the reparametrization invariance,...
Be based on Heavy Ion Collisions, I focus on the chiral anomaly effect eg:CME or CVE in magnetic hydrodynamics. Due to chiral anomaly ,there will be many special features ,I will introduce possible new wave models with the CVE in magnetic hydrodynamics.
We study the anomaly-induced effects of dense matter under rotation. We show that the chiral perturbation theory under rotation has the topological term that accounts for the chiral vortical effect. We find that, due to the presence of this new term, the ground state of QCD under rotation is the chiral soliton lattice (CSL) of the neutral pion or $\eta^{\prime}$ meson. This state is a periodic...
We investigate the influence of rotation on the chiral condensate in strongly interacting matter. We develop a self-consistent theoretical framework to study the inhomogeneous chiral condensate and the possible chiral vortex state in rotating finite-size matter in four-fermion interaction theories. For sufficiently rapid rotation, the ground state can be a chiral vortex state, a type of...
Quarkonia are excellent probes for studying the properties of quark-gluon plasma formed in relativistic heavy-ion collisions at RHIC. In order to fully understand the observed suppression of quarkonium production in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV, it is essential to understand well the cold nuclear matter (CNM) effects on the quarkonium production. Collisions of p+Au at...
Experiments at RHIC and the LHC have lately reported intriguing results that indicate the presence of collectivity in small collision systems. The first hints originated from two-particle azimuthal correlations studies. The charge dependent part of such correlations is studied using the balance function in the relative pseudorapidity (∆η) and azimuthal angle (∆φ) of the particle pair. This...
We reconstruct the freeze-out state of the fireball produced in central Au+Au or Pb+Pb collisions in the energy range from 7.7 GeV up to 2760 GeV per colliding nucleon pair. The data stem from the RHIC beam energy scan programme and from the LHC. Transverse momentum spectra of protons, antiprotons, charged pions and kaons have been fitted. Blast-wave model is used. Resonance decays are fully...
Validation of the Chiral Magnetic Effect (CME) in the quark-gluon plasma (QGP) produced in heavy-ion collisions can provide key insights into anomalous transport in QGP and the connections between chiral symmetry restoration, axial anomaly and gluonic topology. Recently, a charge-sensitive correlator, $\mathrm{R_{\Psi_m}(\Delta S)}$ [1], designed to discern between background- and CME-driven...
In this work, we have presented the collision energy, multiplicity and system size dependence of chemical freeze-out parameters such as chemical freeze-out temperature ($T_{\rm ch}$) and strangeness saturation factor ($\gamma_{s}$). These parameters are obtained by analysing the particle ratios at different Large Hadron Collider (LHC) energies using statistical thermal model (THERMUS). Here,...
Cumulants of net charge fluctuations and their correlations at vanishing values of the charge chemical potentials ($\mu_{B,Q,S}=0$) provide the basis for Taylor expansions of various thermodynamic observables at non-zero values of the chemical potentials. At $\mu_{B,Q,S}=0$ continuum extrapolated results for these cumulants can directly be compared with charge fluctuations and correlations...
We study the production of pions, kaons, and (anti-) protons in A Multi Phase Transport (AMPT) Model in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 27, and 200 GeV. We present the centrality and energy dependence of bulk observables such as invariant yields as a function of transverse momentum $p_T$, particle yields $dN/dy$, average transverse momentum $\langle p_T \rangle$ and various particle...
Commonly, only low-$p_{\perp}$ sector is used to infer the features of initial stages before QGP thermalization. On the other hand, recently acquired wealth of high-$p_{\perp}$ experimental data paves the way to utilize the high-$p_{\perp}$ particles energy loss in exploring the initial stages. However, the results of such explorations are up to now either inconclusive or questionable. We here...
We present our continuum extrapolated lattice QCD results for the cross-correlators of baryon number, electric charge and strangeness, and compare them to calculations from the Hadron Resonance Gas (HRG) model with the most up-to-date hadronic spectrum. We analyze the contributions to these observables from hadronic correlations and self-correlations, and their relation to experimentally...
Charm and beauty are heavy quarks with observed masses of
1.28 GeV/c 2 and 4.18 GeV/c 2 respectively. They are produced
in initial hard scattering processes. Due to their small
formation time (∆t~0.1 fm/c) as compared to the formation
time of QGP ( ∆t~0.3 fm/c) at the LHC, they experience all the
stages occuring during the time evolution of the hot and dense
medium produced in heavy-ion...
Heavy quarks (charm and beauty) are effective probes to investigate the properties of the hot and dense strongly-interacting medium created in heavy-ion collisions as they are produced in high-energy hard partonic scattering processes occurring in the early stages of the collision. Due to their long life time, they probe all the stages of the medium evolution interacting with its constituents...
The production of charm quarks occurs predominantly in hard scattering processes in the earliest stages of a heavy-ion collision, and due to their relatively long lifetimes they experience the full evolution of the system. In ALICE, charmed mesons ($D^0$,$D^+$,$D^{*+}$ and $D_{s}^{+}$) are reconstructed in their hadronic decay channels, allowing the full kinematic information of the original...
Because of their early production, charm quarks are sensitive to the entire evolution of the system created in ultra-relativistic collisions of heavy ions. In particular, charm quark elliptic flow (v2) is a valuable tool for study of charm transport in the quark-gluon plasma (QGP). Recent results from the STAR experiment show that in 10-40% central Au+Au collisions at the top RHIC energy the...
Interactions between hard partons and the quark-gluon plasma range from frequent soft collisions to rare large angle scatterings. The larger number of soft interactions makes possible an effective stochastic description of parton-plasma interactions in terms of drag and diffusion transport coefficients [1]. We build on the methodical division between soft and hard parton-plasma interactions...
The Compressed baryonic matter (CBM) experiment at the future acceleratorFacility for anti-proton and ion research (FAIR) in GSI Germany aims to explore the QCD phase diagram in the very high net-baryon density. The Muon Chamber (MuCh) system would facilitate detection of probes like charmonium (J/ψ) and low mass vector mesons (LMVM) via di-leptonic decay channel. The CBM ...
Based on the state-of-the-art Monolithic Active Pixel Sensor (MAPS) technology, the silicon pixel detector has been successfully applied in the STAR Heavy Flavor Tracker (HFT) for the first time since early 2014. The HFT allows precise measurements of open heavy flavor hadron production in heavy-ion collisions over a wide range of transverse momentum at RHIC. After the 2$^{\rm{nd}}$ long...
Dielectron production is suggested as an excellent probe of the hot, dense and strongly interacting medium (QGP) created in relativistic heavy-ion collisions due to their minimal interactions with the medium and the final state hadrons. Dielectrons can be produced at different evolution stages of the collision system. Different invariant mass ranges are sensitive to different physics...
Dielectrons are excellent probes of the Quark-Gluon Plasma (QGP) created in high-energy heavy-ion collisions. Because they can be produced at all stages of the collision system evolution and do not interact with the medium strongly, dielectrons carry the information from the initial stage to the final stage. In the low mass region (LMR, $\rm M_{ee} < M_{\phi}$), the mass spectra of vector...
The medium generated by non-central nuclear-nuclear collision would have a large angular momentum. Due to the spin-orbit coupling, spin directions of particles formed by recombining quarks from the plasma could reflect the spin direction aligned with the angular momentum of the system. Global polarization is expected to lead to the understanding of the physical properties of QGP because it is...
Oskari Saarimäki for the ALICE collaboration
We present the dijet invariant mass distribution in pp and p--Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV measured by ALICE. We study the dependence of the dijet invariant mass on event multiplicity in both collision systems, to explore cold nuclear matter effects or possible medium modifications in small collision systems. We measure...
Rapidity-odd component of directed flow ($v_{1}$) measurement at various beam energy gives a new insight on the properties of the medium created in heavy-ion collisions. Both hydrodynamic and nuclear transport models indicate that $v_{1}$(y) is sensitive to the details of expansion during the early stages of collision fireball. In this poster, we will present directed flow ($v_{1}$) as a...
Micropattern gaseous detectors (MPGDs) are a group of modern gaseous ionizing detectors consisting of microelectrode structures developed to overcome many of the difficulties of traditional gaseous detectors such as multiwire proportional chambers. The gas electron multiplier (GEM) is one of the most prolific MPGDs currently in use and slated to be used for many future detectors or current...
We examine the relativistic perfect fluid limit,
defined as the fastest possible local equilibration, in a medium with
polarizeability, defined as a non-zero local equilibrium partition of
angular momentum into spin and vorticity.
We show that the Lagrangian approach is best suited to analyzing this situation, as
it can be used to efficiently avoid issues such as the breakdown
of...
DREENA framework is based on our dynamical energy loss formalism, which takes into account finite size, finite temperature QCD medium consisting of dynamical (moving) partons. Both radiative and collisional energy losses are calculated under the same theoretical framework in the dynamical energy loss formalism, which is applicable to both light and heavy flavor observables. We generalized the...
The quark gluon plasma (QGP) produced in high-energy nuclear collisions is known to behave like a perfect fluid. In hydrodynamic simulations at RHIC and the LHC energies, space-time evolution of the QGP is usually described in expanding coordinates. On the other hand, in SPS and RHIC-BES energies, Cartesian coordinates are used for effective description of hydrodynamic expansion. However, the...
We study the far-from equilibrium shear viscosity as present in the early stage of a heavy-ion collision. Our investigation is based on applying the AdS/CFT correspondence to a time-dependent Vaidya spacetime. A generalization of the entropy density to the non-equilibrium regime is necessary for a consistent description. Throughout the evolution, we observe significant deviations in the shear...
In a collision of two identical heavy-ions, the participant zone formed from the overlapping region of the two colliding nuclei contains unequal number of nucleons from each nucleus due to fluctuations. Consequently, the participant zone has a non-zero momentum in the centre of mass frame of the colliding nuclei, causing a longitudinal asymmetry. Using data in Pb-Pb collisions at centre of...
Electrical properties of QCD plasma is an important tool to understand the behaviour of strongly interacting matter in different physical conditions. It will help us to understand the effect of electromagnetic interaction with strongly interacting QCD plasma. Recently, it has been shown that a strong magnetic field is created during heavy ion collisions. Thus it is interesting to study the...
At the early stage of heavy ion collisions, non-trivial topologies of the gauge fields can be created resulting in an imbalance of axial charge density and eventually separation of electric charges along the direction of the magnetic field produced in such collisions. This process is called the chiral magnetic effect (CME). In this work we implement such a charge separation at the partonic...
It is reported recently that an intriguing behavior of the anisotropic flow coefficients in ultra-central Pb-Pb collisions at the LHC. Elliptic flow in ultra-central collisions is driven mainly by fluctuations rather than collision geometry. Therefore, magnitudes of elliptic flow and triangular flow coefficients are almost identical. Some hydrodynamic models, which have been successful in...
Measurements of heavy-flavor hadron production and elliptic flow ($v_{2}$) provide unique and indispensable information for understanding the properties of the QGP. Recent STAR measurements indicate that in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 200 GeV $D^{0}$ mesons develop large $v_{2}$ similarly as light-favor hadrons, implying that charm quarks interact strongly with the...
Charm and beauty quarks (heavy flavours) are produced in hard scattering processes in the early stages of heavy-ion collisions, and propagate through the hot and dense QCD matter (QGP) produced as a consequence of the collision. Therefore, they are sensitive probes to characterize the QGP properties.
The measurement of the elliptic flow (${v_{2}}$) of open heavy-flavour particles at low...
Forward hadron lead/scintillator sampling calorimeter (Projectile Spectator Detector, PSD) consisting of 44 longitudinally segmented modules is developed and already constructed for the future Compressed Baryonic Matter (CBM) experiment at FAIR. The original approaches in the energy calibration with cosmic muons and in the signal analysis are proposed. The longitudinal segmentation of...
Strangeness enhancement in central heavy-ion collisions (A+A) relative to proton-proton interactions (pp) has long been a well-recognized signature for QCD deconfinement or the formation of Quark Gluon Plasma (QGP). The energy scan program at the Relativistic Heavy Ion Collider (RHIC) in BNL or at CERNs' Super Proton Synchrotron (SPS) have presented evidence that are typical of the enhanced...
Studies of collisions of highly accelerated ions are the key to understand the creation of quark matter. Experimental physicists put considerable effort in collecting information characterizing the various processes occurring during such collisions. In order to describe such scenarios, complex models have been constructed, one of them being the EPOS approach. It applies Parton-based...
An interesting strong dependence on charged-particle multiplicity ($n_{ch}$) of $J/\psi$ and $\Upsilon$ production at the LHC and $J/\psi$ at RHIC has been observed. These measurements provide basic information about particle production mechanisms, especially on an interplay between hard and soft processes (multiple parton interactions, string percolations, color reconnection). In order to...
Collision centrality for large heavy ion systems is well defined
both theoretically and experimentally, but the same is not necessarily
true when very asymmetric systems, like p/d+A, collide. In light of
some surprising result on the centrality dependence of high transverse
momentum observables in p/d+A collisions at RHIC and LHC,
the very concept of the geometrically inspired centrality...
Elliptic flow is one of the most important observables in the relativistic heavy ion collisions. It can provide us opportunities to study the early evolution of the expanding system. In this poster, we will present elliptic flow of identified particles ($\pi^{\pm}$, $K^{\pm}$, $p$($\bar{p}$), $K_{S}^{0}$, $\Lambda$($\bar{\Lambda}$), $\phi$, $\Xi^{-}$($\bar{\Xi}^{+}$),...
The study of hadronic resonances such as $\rm{K}^{*}$ and $\phi$ provides a unique tool to investigate the interplay of re-scattering and regeneration effects in the hadronic phase of heavy-ion collisions. As the $\rm{K}^{*}$ has a lifetime comparable to the lifetime of the hadronic phase, one would expect to observe the effects of re-scattering and regeneration processes in the measured...
Recent observations of Quark-Gluon Plasma (QGP)-like conditions in high-multiplicity pp collisions from ALICE experiment at the LHC warrants an introspection whether to use pp collisions as a baseline measurement to characterize heavy-ion collisions for possible formation of QGP droplets. A double differential study of the identified particle production and freeze-out scenario of ...
The interplay between the magnetic and electric field in heavy-ion collisions at high energy results in the charge separation, the phenomenon is known as Chiral Magnetic Effect (CME). Event-by-event charge separation measurements in Pb-Pb collisions at √sNN = 5.02 TeV will be presented. The sum of positive charge fraction on left side and negative charge fraction on right side of the dumbbell...
In relativistic heavy-ion collisions, a strongly interacting medium known as the Quark Gluon Plasma (QGP) is produced. Quarks and gluons from incoming nuclei collide to produce partons at high momenta early in the collisions. By fragmenting into collimated sprays of hadrons, these partons form `jets'. The resulting jets, which in vacuum are well understood within the framework of...
The extraction of thermal freezeout parameters from measured hadron yields
and their higher moments have met with considerable success within the frame-
work of hadron resonance gas models. The standard assumption in such studies
is to consider a constant freezeout parameter set which is extracted by chi-square
fit to data. However, in reality, thermal conditions at freezeout need not be...
We study [1] the suppressions of high transverse momentum single hadron and dihadron productions in high-energy heavy-ion collisions based on the framework of a next-to-leading-order perturbative QCD parton model combined with the higher-twist energy loss formalism [2,3]. Our model can provide a consistent description for the nuclear modification factors of single hadron $R_{AA}$ and dihadron...
Within a multi-phase transport model with string melting scenario, jet transport parameter $\hat{q}$ is calculated in Au+Au collisions at $\sqrt{s_{NN} } $= 200 GeV and Pb+Pb collisions at $\sqrt{s_{NN} } $= 2.76 TeV. The $\hat{q}$ increases with the increasing of jet energy for both partonic phase and hadronic phase. The energy and path length dependences of $\hat{q}$ in full heavy-ion...
In recent years, factorization breaking of flow coefficients in transverse momentum has been measured by CMS Collaboration [1] to understand the transport properties of QGP. The factorization ratio $r_n$ measured in Pb + Pb collisions at LHC represents the decorrelation of the event plane angle in different transverse momentum regions. When $r_n = 1$, which implies the coincidence of the...
“Hybrid Hadronization” is a new Monte Carlo package to hadronize systems of partons. It smoothly combines quark recombination applicable when distances between partons in phase space are small, and string fragmentation appropriate for dilute parton systems, following the picture outlined by Han et al. [PRC 93, 045207 (2016)]. Hybrid Hadronization integrates with PYTHIA 8 and can be applied to...
LHCb has the unique capability to study collisions of the LHC beams on fixed targets. Internal gas targets of helium, neon and argon have been used so far to collect samples of proton- and Pb-gas collisions corresponding to integrated luminosities up to 0.1 pb$^{-1}$. Results on open and hidden charm productions will be presented, which can provide crucial constraints on cold nuclear matter...
for the ALICE Collaboration
Anisotropic flow provides important constraints on the initial conditions and the transport properties of the medium created in heavy-ion collisions. The flow coefficients of higher order harmonics are sensitive to viscous damping [1] and might hinder so-called "acoustic peaks" in flow harmonic power spectrum in analogy to Cosmic Microwave Background in...
Near the QCD critical point (CP), critically slow processes can invalidate the conventional (dissipative) hydrodynamic description, which simply integrates out all non-hydrodynamic modes. We explore the critical dynamics near the QCD CP with the novel Hydro+ framework [1] which extends the conventional hydrodynamic description by coupling it to additional explicitly evolving slow modes. Their...
Recently physics of thermal fluctuations of hydrodynamic fields, namely the hydrodynamic fluctuations, in high-energy nuclear collisions are actively discussed. In this talk I will discuss new modification terms [1] in fluctuation-dissipation relation (FDR), which determines the power of hydrodynamic noise fields, and also discuss its importance in the point of view the fluctuation theorem...
It is well established that the spatial asymmetries of the overlap region in the initial state of a heavy ion collision, together with their fluctuations, are quite faithfully translated into final-state momentum anisotropies by a fluid-dynamical evolution. We investigate the relationship between initial-state eccentricities and final-state anisotropic flow harmonics for a simplified...
In heavy ion collisions, the transverse size or centrality of the QGP is not a boost-invariant concept. Due to forward-backward multiplicity fluctuations, the centrality of the system, defined as $N_{\mathrm{ch}}$ in a given $\eta$ range, also fluctuates in the longitudinal direction. This longitudinal fluctuation leads to decorrelation of centrality along $\eta$, analogous to the...
The observation of multi-particle azimuthal correlations in high-energy small-system collisions has led to intense debate on its physical origin between two competing theoretical scenarios: one based on initial-state intrinsic momentum anisotropy (ISM), the other based on final-state collective response to the collision geometry (FSM). To complement the previous scan of asymmetric collision...
The Generalized High Twist approach has been established to investigate the radiative parton energy loss in deeply inelastic scattering off a large nucleus. The parton undergoes multiple medium parton scatterings and medium-induced radiation after scattering with the virtual photon. In the calculation of radiative energy loss, we relax the approximation in High Twist approach that the radiated...
Fluctuations in physics observables and flow effects in heavy-ion collisions have been topics of particularly interest in recent years as they may provide important signals regarding the formation of quark-gluon plasma, the existence of a critical point and the evolution of the system. Moreover, the fluctuations and correlations measured in the final stage have their sources at least partly ...
We study the medium-induced gluon emission process experienced by a hard jet parton propagating through the dense nuclear matter in the framework of deep inelastic scattering off a large nucleus. We work beyond the collinear rescattering expansion and the soft gluon emission limit, and derive a closed formula for the medium-induced single gluon emission spectrum from a heavy or light quark jet...
Motivated by the recent lattice result, we study the Landau gauge gluon propagators in dense two-color QCD at quark chemical potential. In order to take into account the non-perturbative effects in the infrared regime, we use the massive Yang-Mills theory which has successfully described the gluon and ghost propagators in the Landau gauge within the one-loop approximation. We couple quarks to...
Hadronic resonances are interesting probes of the hot and dense matter created in heavy-ion collisions. Due to their short lifetimes, resonances
are useful tools to understand the particle production mechanisms and the properties of the hadronic phase. Resonance yields are expected to be modified due to the interaction of their decay daughters within the hadronic medium via the re-scattering...
In this talk, we will review the basics of 3+1d quasiparticle anisotropic hydrodynamics (aHydroQP) and highlight some phenomenological comparisons with experimental data at both 2.76 TeV and 200 GeV. We will then present preliminary comparisons of the femtoscopic Hanbury-Brown-Twiss (HBT) radii using aHydroQP. We will show comparisons of the HBT radii and their ratios between aHydroQP and the...
In relativistic heavy-ion collisions, quark-gluon plasma can have a supersonic motion in the longitudinal direction. The quark-gluon plasma also has barotropic equation of state, negligibly small $\eta/s$ ratio, and irrotational velocity profile (specially in the central collisions, where there is no net initial angular momentum). Thus it can be used to construct an analog model of gravity,...
The primary source of high transverse momentum (>4-5GeV/c) direct photons is the initial hard scattering of partons, specifically the quark-gluon Compton scattering process. This has been validated not only in hadron-hadron, but also in heavy ion collisions (see for instance PRL 109 (2012) 152302), where the observed yields were proportional, as expected, to the number of binary...
The gradient expansion solutions to hydrodynamic equations are found to be divergent in many cases. The application of resurgence theory rescues the divergent series solutions and reproduces hydrodynamic attractors in Bjorken flow[1,2] and Gubser flow[3,4]. In this talk, I will first present my result of Borel-resummed hydrodynamics in a different situation, a viscous fluid system that...
The main goal of the CBM experiment at FAIR is to study the behavior of nuclear matter at very high baryonic density. This includes the exploration of the high density equation of state, search for the transition to a deconfined and chirally restored phase, critical endpoint. One of the promising diagnostic probes for these new states is the enhanced production of multi-strange...
Identified light flavour particles, such as the $\pi$, K, $\phi$ mesons and the p, $\Lambda$, $\Xi$ baryons, constitute interesting probes to investigate the collective behaviour recently observed in small collision systems. The underlying mechanisms of light flavour production are currently not well understood, and the mechanisms are explained in the framework of different models. pQCD...
Heavy-flavor quarks created in ultra-relativistic heavy-ion collisions are mostly produced in hard QCD processes during the early stages of the reaction and their production is largely unaffected in the later
stages. They interact with the hot nuclear matter throughout the whole evolution of the systems via semi-hard and soft processes such as energy loss via gluon radiations and collisions....
The Quark Gluon Plasma (QGP) is a state of matter at extremely high energy density, where the quark and gluon constituents of nucleons become deconfined. Although there is strong evidence at RHIC and the LHC that the QGP is created in A+A collisions, it was initially assumed to be absent in smaller systems, such as p+p and p+A collisions. However, the observation of flow-like correlations in...
We study the fluctuation of shape-deformation as currently implemented in MC-Glauber-like models and their consequences on the magnitude of initial-state eccentricities. We show that for both deformed and spherical colliding species, there are large fluctuations in the deformation that emerge event by event. We characterize these deformations with the ratio of the largest and smallest...
Many great efforts have been made to investigate the Chiral Magnetic Effect (CME) and Chiral Magnetic Wave (CMW), which reply on the existence of extremely large electromagnetic fields in relativistic heavy-ion collisions.
However, the current main difficulty of measuring the CME signal is some backgrounds which we do not understand clearly. To isolate the influence of those backgrounds,...
In this talk, I will present a new procedure for dynamically generating conserved charges (baryon number, strangeness, and electric charge) to supplement an arbitrary initial condition for ultrarelativistic heavy ion collisions. This algorithm, which we denote ICCING (Initial Conserved Charges in Nuclear Geometries), treats an initial distribution of energy density as if it were composed...
The lifetimes of short-lived hadronic resonances are comparable to the hadronic phase of the medium produced in high-energy collisions. Thus, these resonances are sensitive to the re-scattering and regeneration processes in the time interval between the chemical and kinetic freeze-out, which might affect the resonance yields. In addition, event shape observables like transverse spherocity are...
One of the important results of the LHC Run 1 was the observation of an enhanced production of strange particles in high multiplicity pp and p-Pb collisions at 7 and 5.02 TeV, respectively. A smooth evolution of yields of strange particles relative to the non-strange ones with event multiplicity has been observed in those systems. Results from Run 2 at the top LHC energy allows us to improve...
To explain the underlying mechanisms involved in particle production and the properties of the strongly interacting nuclear matter produced in high multiplicity p+p collisions, one can use two particle azimuthal correlation method as an important tool. We present here measurements of two particle azimuthal correlation with neutral pion$(\pi^0)$, neutral kaon$(k^0)$ and proton as trigger...
Direct photons from Compton and annihilation hard processes, produced in hard scatterings of partons from incoming nucleons, are unique colourless probes of QCD processes. The measurement provides a handle for testing perturbative QCD predictions and constrain the parton distribution functions.
In this contribution, we present the measurements of isolated photon cross section in pp collisions...
Isolated Photon-Hadron Correlations in pp and p--Pb Collisions at $\sqrt s_{\rm NN}$ = 5 TeV in ALICE.
Fernando Torales Acosta on behalf of ALICE collaboration.
The measurement of isolated photon-tagged correlations of jets and jet fragments is a promising channel for the study of partonic energy loss in heavy-ion collisions. We use a combination of isolation and electromagnetic...
In the early and hottest phase of nucleus-nucleus collisions the formation of a Quark-Gluon Plasma (QGP) is expected. Several QGP induced effects, such as the melting of charmonium states due to color screening or the recombination of uncorrelated charm and anti-charm quarks, can influence charmonium yields. Recent ALICE measurements of charmonium nuclear modification factor in Pb--Pb...
The understanding of cold nuclear matter (CNM) effects are essential to study the properties of a state of deconfined quarks and gluons, the quark-gluon plasma, created in relativistic heavy-ion collisions. CNM effects can be studied in p-Pb collisions.
Furthermore, some results in high-multiplicity p-Pb collisions suggest collectivity similar to that in Pb-Pb collisions. For J/$\psi$...
Polarization is a key observable to determine the quarkonium production mechanism in hadronic elementary collisions. Its very small value measured at the LHC has been challenging the commonly-used theoretical models and it still represents a major standing issue in the field.
On the other hand, phenomenological studies have shown that primordial quarkonium in heavy-ion collisions can be...
The cross section for coherent J/$\psi$ photonuclear production in ultra-peripheral collisions (UPC) at the LHC is sensitive to the low x behaviour of the gluon distribution function of the interacting lead nuclei and provides important constraints on the initial stages in heavy ion collisions.
The measurement of this process by ALICE in Pb-Pb UPC at forward rapidity using Run 2 data at...
In high-energy (proton-proton) pp collisions, there can be a substantial contribution from Multi-Parton Interactions (MPI) in particle production mechanisms. In this case, several interactions at the partonic level occur in a single pp collision and this implies a correlation between the particle production and the total event multiplicity. At LHC energies, MPI might occur at hard momentum...
The measurement of jet shapes such as the angularity, the momentum dispersion and the difference between the leading and subleading jet constituents track momentum will be presented. The measurements were done in pp collisions at $\sqrt s$ = 5 TeV and will be compared to previous measurements by ALICE at $\sqrt s$ = 7 TeV. These jet structure observables probe the radiation pattern of jets....
In this talk the second major software release of the JETSCAPE collaboration will be described. The Jet Energy-loss Tomography with a Statistically and Computationally Advanced Program Envelope (JETSCAPE) Collaboration is developing a complete event generator for heavy ion collisions to be used by the wider community. In this talk we highlight the performance of the year-2 release of the...
Several experimental observables, sensitive to the evolution of the system after nuclear collisions, reveal important information about the properties of the QGP. Among such observables is the production rate of strange quarks, which were originally predicted to be produced with higher probability in a QGP scenario with respect to a pure hadron gas scenario. Studies of strangeness production...
The dynamical models near the critical point are important tools to study the critical phenomena for RHIC BES program. However, the related model calculations depends on various parameters and inputs. In this talk, I will focus on the universal behavior of the dynamical evolving systems near the critical point, which is insensitive to various parameters and input in the model calculations.
...
First, we recall that close to the chiral limit, and below the critical temperature, the long wavelength effective theory of QCD is not ordinary hydrodynamics, but SU(2)xSU(2) superfluid hydrodynamics (Son 2000). In this theory the usual hydrodynamic variables such as energy are momentum are augmented by long wavelength pions. When the pion is massive, the effective theory reduces to normal...
$\Lambda$ and $\bar{\Lambda}$ polarization in heavy-ion collisions at BES RHIC energies is studied within the microscopic transport model UrQMD. Two approaches, (1) thermal and (2) axial anomaly approach, are considered. We trace the formation and space-time evolution of vorticiity and helicity patterns in details. This study demands a complex analysis of the fireball conditions including...
Principal Component Analysis (PCA) is a mathematical tool that can capture the most important information (variance) in data. Recently, CMS collaboration applied the PCA technique to analyze the data in Pb+Pb collisions, and a non-zero subleading mode has been extracted and interpreted as arising from subleading eccentricity [1][2]. In this talk, we study the performance of PCA method in the...
Spin polarization of $\Lambda$ hyperon has been observed by STAR in non-central heavy-ion collisions [1,2,3]. Among these measurements, the global polarization reflects the bulk-averaged value of the vorticity, while the local polarization probes more detailed structure of the vorticity field.
We have studied the $\Lambda$ polarization in heavy-ion collisions using a multi-phase transport...
One of the main aims of beam energy scan (BES) program at relativistic heavy ion collider (RHIC) is to locate the position of critical point in the ($T-\mu_B$) plane of QCD where the first order transition ends and cross over transition begins. Here $T$ denotes temperature and $\mu_B$ stands for baryonic chemical potential.At the critical point, quantities like specific heat and susceptibility...
The presence of coherence in pion emission will suppress the strength of the final-state pion HBT correlations. The recently observed significant pion HBT suppressions in both Pb-Pb and pp collisions at the LHC indicate the pion emissions may be partially coherent in such violent collisions. In this talk we will show that the coherence in particle emission can give rise to a remarkable...
The High Acceptance DiElectron Spectrometer (HADES) and the Compressed Baryonic Matter experiment (CBM) are dedicated to study strongly interacting matter at high baryon densities and moderate temperatures. Being penetrating probes, dielectrons are a key observable to get direct access to the fireball.
Currently the HADES experiment is located at SIS 18 at GSI, Darmstadt and will be moved...
In high energy heavy-ion collisions, the strong electromagnetic (EM) fields of the nuclei can produce energetic, high-density photon fluxes, leading to photon-induced interactions. Recently, significant enhancements of $e^{+}e^{-}$ pair and J/$\psi$ production at very low transverse momentum ($p_{T}$) were observed by the STAR [1, 2] and ALICE [3] collaborations in peripheral hadronic A+A...
Low-mass dielectrons play a key role in the understanding of the chiral-symmetry restoration and in the study of the Quark-Gluon Plasma (QGP) created in relativistic heavy-ion collisions. In the intermediate-mass region, the measurement of thermal dielectrons from the QGP is nevertheless very challenging at the LHC due to the dominant contribution of e$^{+}$e$^{-}$ pairs from open-charm and...
The measurement of low-mass $e^+e^-$ pairs is a powerful tool to study the properties of the Quark-Gluon Plasma (QGP) created in ultra-relativistic heavy-ion collisions. Since such pairs do not interact strongly and are emitted during all stages of the collisions, they provide information about the full time evolution and dynamics of the medium created.
Measurements in pp collisions are the...
Reconstructing the jet transverse momentum is a challenging task, particularly in heavy-ion collisions due to the large fluctuating background from the underlying event. While the standard area-based method effectively corrects for the average background, it does not account for region-to-region fluctuations. These residual fluctuations are handled in an unfolding procedure following the...
Recent STAR measurements of global hyperon polarization in AuAu Collisions at the Relativistic Heavy Ion Collider (RHIC) have attracted significant interest and generated wide enthusiasm. The data present an intriguing puzzle, showing a difference in the global spin polarization between hyperons and anti-hyperons, especially at relatively low collision beam energy. One possible cause of this...
The main goal of NICA/MPD is to investigate the hot and dense baryonic matter in heavy-ion collisions over a wide range of atomic masses, from $Au+Au$ collisions at a center-of-mass energy of $\sqrt{s_{NN}} = 11GeV$ (for $Au^{79+}$) to proton-proton collisions with $\sqrt{s_{pp}}= 20GeV$.
Electromagnetic calorimeter (ECal) is an important detector of the MPD to identify electrons, photons...
Owing to their large mass, charm quarks are predominantly produced through initial hard scatterings in heavy-ion collisions. Therefore, they can serve as penetrating probes to study the intrinsic properties of the hot medium created in heavy-ion collisions. However, Cold Nuclear Matter (CNM) effects can also affect the charm quark production in nuclear collisions with respect to p+p...
The ALICE detector at the Large Hadron Collider (LHC) is optimised for the inverstigation of the Quark-Gluon Plasma (QGP) created in heavy-ion collisions. Charm quarks are effective probes to elucidate the properties of the QGP. They are dominantly produced at the initial stage of the collisions via hard partonic scattering processes and experience the whole evolution of the...
Charm quarks, owing to their large mass, are predominantly created through initial hard scatterings in relativistic heavy-ion collisions and thus are ideal probes to study early time dynamics of these collisions. Recent results from STAR show that the slope of $D^{0}$ mesons directed flow ($v_{1}$) versus rapidity is about 25 times larger than that of charged kaons, providing important...
The $\phi$ vector mesons have much smaller hadronic cross section which makes them less influenced at late-stage interactions than other hadrons [1-4]. Thus their anisotropies like the elliptic flow should be small if the system is always in a hadronic phase. This, in turn, makes $\phi$ meson $v_2$ especially sensitive to the energy where quark-gluon plasma turns off. Measurements from STAR at...
Due to their large masses, heavy quarks are produced in the early stages of relativistic heavy-ion collisions via initial hard scatterings. Therefore, they are considered as effective probes of the hot and dense Quark-Gluon Plasma (QGP) formed in such collisions and witness the full evolution of the QGP. In pp collisions, the measurement of charm and beauty hadron production cross-sections can...
In heavy-ion collisions, charm and beauty quarks are produced in the initial hard partonic scattering and interact with the hot and dense QCD matter (QGP).
Therefore, measurements of heavy-flavour production provide relevant information on the properties of the QGP. The QCD predicts that partons lose energy via collisions with the plasma constituents and via gluon radiation, and the magnitude...
One of the main goals of RHIC beam energy scan program is to search for the signature of the QCD critical point in heavy-ion collisions. It is predicted that the local density fluctuations near critical point exhibit power-law scaling, which can be probed with a intermittency analysis of the scaled factorial moments ($F_{q}$) for charged particles. The power-law behavior of $q^{th}$ order...
The charge asymmetry ($A_{\rm ch}$) dependence of the $\pi^{+}$ and $\pi^{-}$ elliptic flow difference, $\Delta v_{2}(A_{\rm ch})\equiv v_{2}^{\pi^{-}}(A_{\rm ch}) - v_{2}^{\pi^{+}}(A_{\rm ch})$, is sensitive to the Chiral Magnetic Wave (CMW). Previous measurements in 200 GeV Au+Au collisions by STAR indicated a positive $\Delta v_{2}(A_{\rm ch})$ slope and, in central and peripheral...
In heavy-ion collisions, the thermalized matter is tilted in the reaction plane as a function of rapidity, while the production profile of partons from hard scatterings is symmetric in rapidity [1]. This leads to a rapidity-odd asymmetry in the medium path length traversed by the hard partons and results in a rapidity-odd directed flow ($v_1$). Measurements of high-$p_{\mathrm{T}}$ hadron...
Fluctuations in conserved charges such as net charge (Q), net strangeness (S) and net baryon (B) are good probes of the QCD phase transition and the critical point [1]. The QCD-based models suggest that the moments of the conserved charge distributions are related to the correlation length of the system as: $\langle (\delta N)^{2} \rangle$ $\sim$ $\xi^{2}$, $\langle (\delta N)^{3} \rangle$...
We present the semi-inclusive measurement of charged jets recoiling from direct-photon and $\pi^0$ triggers in central Au+Au collisions at $\sqrt{s_\mathrm{NN}}=200$ GeV, using a dataset with integrated luminosity 13 nb$^{-1}$ recorded by the STAR experiment in 2014. The photon and $\pi^0$ triggers have $9<\rm E_{T}^{trig}<20$ GeV. Charged jets are reconstructed with the anti-$\rm{k_{T}}$...
Cumulants of conserved quantities are the powerful tools to study the QCD phase structure. According to the Lattice Gauge Theory calculations, at vanishing baryon chemical potential ($\mu_{B}$) a "smooth crossover" for the transition from quark-gluon plasma to hadronic system occurs in heavy-ion collisions [1]. One of the possible experimental ways to search for the evidence is to analyze the...
Large uncertainty for initial geometry eccentricity has been found in small systems. Calculations which include subnucleon structure have been found substantially different with standard Glauber model calculations. This will make it difficult to address the physics origin of long-range angular correlations in small systems, which may come from the initial-state momentum correlations or...
The main goal of heavy-ion collisions is to study the deconfined phase predicted by quantum chromodynamics, the Quark Gluon Plasma.In the presence of the QGP, theories predict the existence of field configurations that could violate parity symmetry locally at a level that could be experimentally measured. In heavy-ion collisions, local parity violation manifests as charge separation along the...
Systematic investigation of charm and bottom productions and their modifications in heavy-ion collisions is crucial for understanding the parton energy loss mechanism inside the hot and dense medium. Electrons from semi-leptonic decays of open heavy-flavor hadrons can serve as a proxy for heavy quarks with the possibility of triggering on them during data taking to gain statistics.
The...
To study the nature of the quark-hadron phase transition, it is important to investigate the space-time structure of the hadron emission source in heavy-ion collisions. Measurements of HBT correlations have proven to be a powerful tool to gain information about the particle emission region. In this study, Levy fits were performed to the measured one-dimensional two-pion correlation functions...
Heavy quarks (i.e charm and beauty quarks) are effective probes to investigate the properties of the hot, dense and strongly-interacting medium, known as the Quark-Gluon Plasma (QGP), formed in ultra-relativistic heavy-ion collisions. Due to their large masses, they are produced in the initial stages of the collision via hard partonic scatterings and hence, they experience the full evolution...
The Compressed Baryonic Matter (CBM) experiment is one of the scientific pillars of the Facility
for Anti-proton and Ion Research (FAIR), which is presently under construction adjacent to GSI,
Darmstadt. The Silicon Tracking System (STS) is the core detector of the CBM experiment, located
inside the superconducting dipole magnet. The main task of STS is to reconstruct the tracks...
The NICA heavy-ion program is aimed in studying the properties of nuclear matter under extreme conditions. A detailed energy and system size scan will be performed in the center-of-mass energy range from 4 to 11 GeV with an emphasis on the study of yields, spectra, azimuthal anisotropy, fluctuations and correlations of multiple probes from electrons and gammas to light (hyper)nuclei.In order...
Genuine multiparticle azimuthal correlations have been used in anisotropic flow analyses to study the properties of the Quark-Gluon Plasma (QGP) produced in ultrarelativistic nuclear collisions. A recently introduced set of observables, based on the measurements of the correlated fluctuations of two different flow harmonics, has allowed the application of new constraints on the properties of...
Instead of using the generating function or Q-cumulant methods for multiparticle correlation studies in heavy ion collisions, we calculate the cumulants directly looping over particle azimuthal angles. It is shown that this method is not possible for central and mid-central AA collisions due to the required computing resource, but possible for smaller collision systems and peripheral AA...
Jets are collimated bunches of hadrons produced from fragmentation and hadronization of hard scattered partons (quarks and gluons) in high energy collisions. Due to the different color charges of quarks and gluons, differences in the fragmentation of the two types of partons are expected. Therefore jets originated from primary quarks and gluons, are predicted to have different properties....
Recent PHENIX measurements indicate that the initial geometry is the cause of the observed positive $v_2$ and $v_3$ in high-multiplicity p+Au, d+Au, and $^3$He+Au collisions at $\sqrt{s_{\rm NN}} = 200$~GeV. These results were obtained using the event-plane method, with the event plane determined in the backward rapidity range and correlated with particles in other sub-events at mid- and...
A jet is a spray of collimated hadrons originated in the fragmentation of an energetic parton. The cross section measurement provides a good test for pQCD calculations. Jet $p_{\rm T}$ spectrum measurement in pp collisions sets a reference for jet quenching study in nucleus-nucleus collisions. In addition, high multiplicity pp collisions show similar collective behavior as found in heavy-ion...
The non-extensive statistical description of the identified final state particles measured in high energy collisions is well-known by it's wide range of applicability. However, there are many open questions that need to be answered, including but not limited to the question of the observed mass scaling of massive hadrons or the size and multiplicity dependence of the model parameters. This...
High-multiplicity pp collisions show similar collective behavior as found in heavy-ion collisions with comparable event multiplicity, such as long-range near-side correlations and the $v_n$ coefficients. In pp collisions, these effects may be caused by multiple-parton interactions or other vacuum QCD effects. Investigating the modification of the jet shape in terms of the event multiplicity...
For Runs 3 and 4, an ambitious upgrade program is ongoing within the ALICE experiment to further explore the properties of the Quark Gluon Plasma.The Muon Forward Tracker(MFT), one of the major ALICE upgrades, aims to add vertexing capability for muon detection at forward rapidity by providing vital track information in front of the absorber of the Muon Spectrometer. MFT will allow to separate...
Net-charge fluctuations in ultrarelativistic heavy-ion collisions are studied, in terms of the variable $\nu_{[+-,dyn]}$, analysing data from pp, p-Pb and Pb-Pb collisions at $\sqrt{s}_{NN}$ = 5.02 TeV and Xe-Xe collisions at $\sqrt{s}_{NN}$ = 5.44 TeV from the ALICE experiment at LHC. Data from various collision systems provide an opportunity to study the dependence of $\nu_{[+-,dyn]}$ on the...
One of the fundamental goals of heavy-ion collision experiment is to map out the temperature $(T_{f})$ and baryon chemical potential $(\mu_{B}^f)$ of the Quantum Chromodynamics (QCD) phase diagram at which chemical freeze-out occurs - a point on the phase diagram when the chemical composition of the system is fixed. The cumulants of conserved quantities (net-charge, net-baryon number,...
The Solenoidal Tracker at RHIC (STAR) enables the possibility of exploring the properties of strongly interacting nuclear matter using the method of femtoscopy. By studying the quantum statistical effects and final state interactions between two particles, one can extract emission source parameters, which is used to describe geometrical and dynamical properties of the homogeneity region. We...
Correlation femtoscopy is a standard technique for the experimental analysis of ultrarelativistic nuclear collisions. The measured two-particle correlation function is clearly non-Gaussian, and so it is often better reproduced by Levy stable distribution than a Gaussian one. It has been suggested that a particular shape of a Levy-stable distribution may help to identify the QCD critical...
Heavy-flavor quarks (charm and beauty) play an important role in probing the Quark-Gluon Plasma (QGP) formed in the heavy-ion collisions. Due to their heavy masses, charm and beauty quarks are formed in hard scattering processes on a timescale shorter than the QGP formation time. Therefore, they experience all the phases of the medium evolution interacting with the medium constituents and...
Transverse Single Spin Asymmetries (TSSAs) manifest themselves through
an azimuthal-angle dependence of particle production relative to the
transverse spin direction of the polarized proton in the reaction
p↑ + p → h + X. In recent years, attention has been given to the interplay
with small-x physics by studying TSSAs in transversely-polarized proton-ion
collisions (p↑+A). Recent...
High-transverse-momentum prompt photons, as colorless objects, do not interact strongly with the medium and provide a direct way to test pQCD and the nuclear PDF. The transverse energy spectra and the nuclear modification factors of isolated photons are measured in pp and PbPb collisions at 5.02 TeV using the CMS detector. The data are compared to JETPHOX NLO calculations and found to be...
With our coupled jet-fluid model, we study the nuclear modifications of full jets and jet structures for single inclusive jets and $\gamma$-jets in Pb+Pb collisions at $5.02$ ATeV and $2.76$ ATeV. The in-medium evolution of full jet shower is described by a set of coupled transport equations including the effects of collisional energy loss, transverse momentum broadening and medium-induced...
We investigate whether the QCD crossover gets stronger as the chemical potential is increased. To this end, we study the chiral condensate and susceptibility in a finite volume scaling study at zero and small chemical potentials. We achieve this by extrapolating these quantities from imaginary $\mu_B$ maintaining strangeness neutrality. We also extrapolate low order fluctuations of conserved...
In 2018, LHCb recorded ~210 microbarn$^{-1}$ integrated luminosity of PbPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV. In this talk, we present the first LHCb measurements of open heavy-flavour and J/$\psi$ productions from this new sample. The momentum resolution of the detector allows to probe the boundary of peripheral and ultra-peripheral collisions by comparing hadro-produced and...
The positive elliptic flow ($v_{2}$) of open heavy-flavour particles observed in semi-central Pb--Pb collisions at LHC energies indicates that heavy quarks suffered strong interactions in the deconfined QCD medium and participated in the collective motion of the medium. Recent observations in high-multiplicity pp and p--Pb collisions show remarkable similarities with Pb-Pb collisions and...
At low temperature and low density, the chiral symmetry is broken dynamically to form hadronic phase. While, at high temperature and/or high density, this symmetry is restored and consequently the quark gluon plasma (QGP) appears. In the QCD phase diagram with temperature $T$ and baryon chemical potential $\mu_B$, it is established from first-principle calculations that the transition from...
A Time Projection Chamber (TPC) is a good candidate as the main tracking device for many experiments.
A TPC measures space points of charged tracks, which provide momentum resolution and particle identification for a variety of measurements.
In high multiplicity environments a TPC has to cope with the build-up of space charge in the drift volume which is created by two major effects;...
The measurement of direct photons at forward rapidity in high-energy proton-nucleus collisions is a key to investigate the high-density parton distribution functions and to understand the initial state of nuclear collisions. Gluon distributions at very small x (below 10$^{-4}$) may reach saturation of the phase space. The Color Glass Condensate is a theoretical framework that describes the...
sPHENIX is a new heavy ion experiment at RHIC and aims to study the microscopic structure of quark-gluon plasma by measuring the Jet modification with different flavors and the possible different suppressions of Upsilons.
Intermediate silicon strip tracker (INTT) is one of the tracking detectors sandwiched between the inner silicon pixel tracker (MVTX) and the outer TPC. INTT consists of two...
Heavy-ion collisions at NICA are well suitable to investigate fundamental problem of strongly interacting matter such as its EOS, bulk properties, state of QCD vacuum, and criticality.
The production of (anti)hyperons is sensitive to the early stage of the collision, thus the degree of partonic collectivity can be tested by means of multi-strange baryon yields, spectra, and anisotropic...
The equation of state of dense nuclear matter, while central in simulations of QCD systems under extreme conditions, is currently inaccessible to first principles calculations. Using relativistic density functional theory, we model the thermodynamics and single-particle equations of motion of nuclear matter over a broad range of temperatures and densities encompassing nuclei, neutron stars,...
A better understanding of parton dynamics in the nucleus, in particular in the small-x region, is extremely important as it is needed to understand the nature of recently observed and unexpected phenomena like particle anisotropies in small collision systems. PHENIX can explore the small and large-x regions in the nucleus through measurements in the muon arms and forward vertex trackers. These...
One of the big puzzles in quarkonia production is how heavy-quark pairs, produced in the initial hard process, hadronize into final quarkonia states. This uncertainty affects the estimation of quarkonia breakup cross sections and color screening in heavy ion collisions. According to Non-Relativistic Quantum Chromodynamics, quarkonia are formed from several intermediate singlet and color octet...
Recently, there have been significant experimental progresses in observing and/or controlling spin-dependent bulk quantities in broad areas in physics, e.g., relativistic heavy-ion collisions, spintronics. Although hydrodynamics is one of the most powerful theoretical frameworks to describe bulk quantities, its extension to a spinful fluid has not been developed well, especially for...
Photon identification in the ALICE EMCal using a neural network and template fit
Alwina Liu for the ALICE collaboration
The measurement of isolated photon-tagged correlations of jets and jet fragments is a promising channel for the study of partonic energy loss in heavy-ion collisions. Isolated photons are an excellent probe because they constrain the parton kinematics of the initial hard...
Jet modification is now understood to be a multistage effect: a parton produced in a high virtuality initial state, radiates a multitude of partons, giving way to a variety of lower virtuality stages. In the lower virtuality stage, higher energy partons are weakly coupled with the medium and continue to scatter and radiate whereas lower energy partons are strongly coupled with the medium and...
In ultra-relativistic nucleus-nucleus collisions a new state of matter where quarks and gluons are not confined into hadrons, the Quark-Gloun Plasma (QGP), is created. The ALICE experiment at the LHC is dedicated to the study of the properties of the QGP. In addition, proton-proton collisions are used as the high energy QCD reference while the study of proton-nucleus collisions provides a...
We study the contribution to the polarization of $\Lambda$ hyperons in relativistic nuclear collisions at high energy from the decays of $\Sigma^*(1385)$ and $\Sigma^0$, which are the predominant sources of $\Lambda$ production besides the primary component, as a function of the $\Lambda$ momentum. Particularly, we determine the longitudinal component of the mean spin vector as a function of...
The system created in high-energy heavy-ion collisions quickly reaches local equilibrium and its evolution is usually modeled with relativistic hydrodynamics. However, the effects of the early, pre-equilibrium stages of system evolution on final-state observables are largely unknown. In this work, we study the effects of pre-hydrodynamic evolution on final-state observables in various...
The Joint Zero Degree Calorimeter Project, JZCap, seeks to deploy new high resolution ZDCs for ATLAS, CMS and possibly other experiments for Run 3 of the LHC. These ZDCs will be radiation hard enough to measure forward neutrons and bremsstrahlung photons during PbPb, pPb and dedicated pp running. The ZDCs are tungsten Cerenkov calorimeters where the active medium consists of fused silica...
In this talk a pair of observables are proposed as alternative ways to study the charge separation induced by Chiral Magnetic Effect (CME) in relativistic heavy ion collisions. They are, the out-of-plane to in-plane ratio of fluctuation of the difference between signed balance functions measured in pairs rest frame, and the ratio of it to similar measurement made in the laboratory frame. Both...
Gluon nuclear PDFs still have large uncertainties in the small-x ($x$<10^{-3}) and small virtuality $Q^2<$50 (GeV/c)$^{2}$ region. Yields from particles coming from these gluons obtained in nuclear collisions are suppressed relative to $p$+$p$ collisions because of initial-state effects such as shadowing, energy loss and gluon saturation. Precise measurement of yields coming from small-x,...
Charm quarks are excellent probes to study properties of the Quark-Gluon Plasma (QGP) created in ultra-relativistic heavy-ion collisions. In particular, measurements of the $D_{s}^{\pm}$ meson production can provide valuable information on the strangeness enhancement in the QGP as well as the charm quark hadronization mechanisms in heavy-ion collisions. In this poster, we will present results...
The production of quarkonia in hadron-hadron collisions occurs at the transition between the perturbative and nonperturbative regimes of QCD, resulting in a rich phenomenology that remains far from being fully understood. $J/\psi$ hadronization dynamics can be studied by measuring the $p_{T}$ fraction, $z \equiv p_{T,J/\psi} / p_{T,jet}$, carried by the $J/\psi$ meson detected inside a jet....
Charm quarks are an ideal probe of the QGP created in heavy-ion collisions as they are produced at very early stages of such collisions and subsequently experience the whole evolution of the system. At STAR experiment, charm quark production can be accessed by direct topological reconstruction of open-charm hadrons thanks to an exceptional spatial resolution of the Heavy-Flavor Tracker...
Various recent measurements of high-multiplicity pp and p-A collisions at the LHC center-of-mass energies have revealed, surprisingly, that these small collision systems exhibit some of the quark-gluon plasma features, e.g. collective behaviour and strangeness enhancement, formerly thought to be achievable only in heavy-ion collisions. A promising method to narrow down the origin of this...
Measurements of the production cross sections of heavy quarkonia, namely J/$\psi$ and $\psi$(2S), in hadron-hadron collisions provide valuable information about yet unsolved questions of Quantum Chromodynamics. The Solenoid Tracker At RHIC (STAR) is a major high-energy nuclear physics experiment at the Relativistic Heavy Ion Collider. Its Muon Telescope Detector, which provides trigger and...
At the end of 2016 the ALICE experiment at the LHC collected data from p--Pb collisions at $\mathrm{\sqrt{s_{NN}}}$=8.16 TeV.
These data represent an important chance to test the emergence of possible initial state effects, by comparing the transverse momentum distributions of identified light hadrons extracted in this dataset to those previously measured in pp and Pb--Pb collisions, in a ...
Short lived hadronic resonances are very useful tools to probe the evolution of high energy heavy-ion collisions. Owing to the short lifetime of resonances $(\sim 10^{-23}$s), their characteristic properties such as mass, width and yield are very sensitive to the collision dynamics and in-medium effects. Multiple resonances have been studied in ALICE, including $\rho(770)$, $K^{*}(892)$,...
Recent measurements of charm baryon production in pp and p-Pb collisions at LHC energies show a baryon-over-meson ratio significantly higher than expectations from Monte Carlo generators tuned to reproduce the lower values measured in ${\rm e}^{+}{\rm e}^{-}$ and ${\rm e}^{\pm}{\rm p}$ collisions. In Pb--Pb collisions at LHC and Au--Au collisions at RHIC, even higher values of $\Lambda_{\rm...
The first RHIC Beam Energy Scan (BES-I) was run from 2010-2014 to search for the turn-off of signatures of the quark-gluon plasma (QGP), evidence of the first-order phase transition, and the possible QCD critical point. The QGP signatures studied in BES-I became insensitive or disappeared at energies below $\sqrt{s_{NN}}$ = 19.6 GeV. The fluctuations in the event-by-event net-proton...
\documentclass{article}
\usepackage[utf8]{inputenc}
\title{Quantitative evaluation of muon track matching efficiency with Muon Forward Tracker and Muon Spectrometer at ALICE}
\author{Kaede Kamano for the ALICE collaboration}
\date{June 2019}
\begin{document}
\maketitle
ALICE has been designed to study the quark-gluon plasma in heavy-ion collisions at LHC. Extensive efforts in...
Many-body systems with chiral fermions exhibit anomalous transport phenomena originated from quantum anomalies. Based on quantum field theory, we derive the quantum kinetic theory for Dirac fermions interacting with an external electromagnetic field in a background curved geometry. The resultant framework is U(1) gauge invariant and local Lorentz and diffeomorphism covariant. In this talk, I...
Quark-hadron continuity [1] is a scenario that the hadronic matter is continuously connected to a color superconducting phase without phase transitions as the baryon chemical potential increases. This scenario is based on the fact that the two phases have the same symmetry breaking pattern, in the spirit of Landau's classification of phases. When we consider quantum phases of matter, it is...
Quarkonia suppression has been long predicted \cite{satz19861} and explored as a defining signature of formation of quark-gluon-plasma (QGP). Various physical processes \cite{satz19861,laine20071,brambilla20081} have been understood to contribute to the dynamics of a Q-$\bar{Q}$ traversing through the QGP. The proper framework to implement a Schr\"{o}dinger equation, which takes into account...
In heavy ion collision experiments at RHIC and LHC, quarkonium yields have been measured at various collision energies. The experimental findings reveal different characteristic behavior: sequential suppression dominates for bottomonium and recombination for charmonium. A comprehensive understanding of this phenomenology requires a genuine quantum mechanical treatment, in particular to capture...
Hadronic resonances are unique and useful probes of ion-ion collision systems. They can be used to study the evolution of the hadrochemistry with system size, including resonance suppression and strangeness enhancement. Resonances can also be used to explore the various mechanisms that influence the shapes of hadron $p_{\mathrm{T}}$ spectra and to search for the possible onset of collective...
The Compressed Baryonic Matter experiment (CBM) and the High Acceptance Di-Electron Spectrometer (HADES) are part of a worldwide research program devoted to study the phase diagram of strongly interacting matter at high baryon densities $\rho_{B}$ and moderate temperatures $T$ in p+A and A+A collisions. One of the major observables addressed by both experiments is dilepton production.
A...
Using a transport model based on BAMPS, we investigate the evolution of magnetic field in a system of charged particles, which is embedded in a cylinder with the periodic boundary condition. We find that when the ratio of the helicity to the magnetic energy goes to a maximum, the system relaxes towards the CKW state with ∇×B∥B and we test the result both in classical plasma and QGP.
Within proton-lead collisions collected by the LHCb detector at nucleon-nucleon center-of-mass energy of 5 and 8.16 TeV, a rich set of open charm hadrons is observed with abundant statistics. Thanks to the LHCb forward acceptance that is complementary to general purpose detectors and excellent performance in particle reconstruction and identification, these charm states are studied down to...
We mainly focus on the effect of rotation on the QCD phase structure in a background magnetic field. We analyze the energy spectra of Dirac fermions in the presence of rotation and magnetic field. We find that the Landau degeneracy is resolved by rotation. A drastic change in the energy dispersion relation leads to the “rotational magnetic inhibition” that is a novel phenomenon analogous to...
The QCD critical point can attract the system evolution trajectory in the QCD phase diagram, which is recognized as the QCP focusing effect[1,2]. To quantify this effect, we employ thermal model and hadronic transport model to simulate the dynamical particle emission along a hypothetical focusing trajectory near the critical point. It is found that the focusing effect can lead to anomalous...
The measurement of reconstructed jets over a wide range in jet energy and jet resolution parameter $R$ is required for comprehensive understanding of jet quenching in heavy-ion collisions. Such measurements are challenging, however, due to the presence of complex, uncorrelated background to the jet signal, and the need to minimize biases in the selected jet population imposed by background...
The chiral magnetic effect is a good observable to investigate the topological and electromagnetic properties of the QGP. But the $\gamma$ correlator, a common observable used to detect the CME, contains both contribution from the CME and its background. This observable can not identify the CME from its background. Recently, a new observable of $R_{\Psi_{m}}$ has been proposed[1-4], which is...
In non-central nucleus-nucleus collisions, an ultra-intense magnetic field reaching 10^15 [Tesla] is generated. Many interesting phenomena such as non-linear QED and Chiral Magnetic Effect are expected to be induced under the field. Nucleus-nucleus collisions are the only one way to generate such a field and to study the field-induced phenomena experimentally.
Di-leptons from virtual photons...
Current measurements of the modification of jets in the quark–gluon plasma necessarily average over the quark–gluon composition of the jets in the sample. This introduces substantial complications in measuring differences of energy loss and modification between quark-initiated and gluon-initiated jets. Additionally, even in the absence of jet modification, a modified quark–gluon fraction of...
Photons and dileptons offer themselves as 'clean' probes of the quark-gluon plasma because they are unlikely to reinteract once produced. Their emission rates are given via the vector spectral function $\rho_{\mu\nu}$, an object that can ultimately be reconstructed by analytic continuation of lattice data. To help scrutinise ensuing systematic uncertainties, we determine the NLO corrections to...
We have investigated the chiral anomalies with transport simulations in a box system. In the box system with the periodic boundary condition under a uniform magnetic field, the chiral magnetic effect and the chiral magnetic wave were simulated based on the spin kinetic equations of motion (SEOM) and the chiral kinetic equations of motion (CEOM), with the latter derived from the SEOM for...
The Compressed Baryonic Matter (CBM) experiment will access a wide range of physics observables for heavy-ion collisions in the region of highest net-baryon densities. One of the core topics of its physics program are the measurement of rare thermal dilepton channels. These EM probes have a very low cross section and therefore need very high statistics and a powerful particle identification....
Over the past years, the observed features in the collisions of small systems which resemble collective flow patterns, are under intense debates. A relevant question is to what extent these observations are related to the real collective evolution of the medium, and if this is the case, the related question is what is the smallest system size which can still accommodate collective behaviour....
In this contribution we investigate the properties of the complete Israel-Stewart equations when perturbed around a global equilibrium state. Such analyses have been previously performed including only the effects of the shear-stress tensor and/or bulk viscous pressure and only using the simplified Israel-Stewart equations (which do not include any second order terms, except the one related to...
The observability of the Chiral Magnetic Effect in heavy-ion collisions has been argued to strongly depend on collision energy because of the variations in the lifetime of magnetic field, the domain size of chiral charge and also on the possibility of formation of a medium with deconfinement and chiral symmetry restoration. While isobar analysis at top RHIC energy is ongoing, in this poster...
The Compressed Baryonic Matter (CBM) experiment aims at exploring the QCD phase diagram at large baryon densities with heavy ion beams in the beam energy range from 2 A GeV to 11 A GeV at the SIS100 accelerator of FAIR/GSI. For charged particle identification that is required by many observables that are sensitive to the phase structure like collective flow, phase space population of rare...
Strangeness production is a classic tool to study properties of the quark gluon plasma (QGP). The ratios of particle yields involving strange particles are often utilized to study various properties of nuclear matter, such as the strangeness chemical potential and the chemical freeze-out temperature. In particular, the yield ratios $(N_{K}N_{\Xi})/(N_{\phi}N_{\Lambda})$ and...
Measurements of long-range, collective azimuthal correlations involving heavy-flavor quarks provide a powerful tool for unraveling the origin of the collectivity observed in small collision systems. In particular, these measurements are sensitive to the early stages of the collisions. As compared to those for light flavor hadrons, large azimuthal anisotropy signals have been observed by CMS...
We study charge-independent (CI) and charge-dependent (CD) two-particle differential number correlation function, $R_{2}( \Delta\eta, \Delta\varphi)$, and transverse momentum correlation function, $P_{2}( \Delta\eta, \Delta\varphi)$, of unidentified ($h^{\pm}$) and identified (i.e. $\pi^{\pm}, K^{\pm}$ and $p\bar{p}$) charged particles produced in pp collisions at $\sqrt{\textit{s}}$ = 2.76...
${\rm W}^{\pm}$ bosons are created in hard scattering processes at the initial stage of heavy-ion collisions and they are insensitive to the presence of the strongly-interacting medium. This makes them clean probes of the initial-state effects in heavy-ion collisions, such as the nuclear modification of the Parton Distribution Functions (nPDFs). Furthermore, their measurement in heavy-ion...
Recent ALICE results on the yield of strange particles in pp and p-Pb collisions reveal the possibility that similar strange quark production mechanisms could be present in all collision systems. The $p_{\rm T}$-dependent baryon-to-meson yield ratio in hadronic and nuclear collisions is sensitive to the collective expansion of the system, the partonic recombination into hadrons, the jet...
Photons and dileptons ($\gamma^{*} \to l^{+}l^{-}$) are unique tools to study the space-time evolution of the quark-gluon plasma (QGP) produced in high-energy heavy-ion collisions.
The space-time evolution of heavy-ion collisions can be calculated using relativistic hydrodynamics and hadronic transport models.
Up to the present time, theoretical models fail to describe the large direct...
Studies of jet energy loss and momentum broadening with photon-jet momentum and angular correlations will be presented, with PbPb data at 5.02 TeV collected by the CMS detector. Photon-jet events provide a means of probing in-medium jet energy loss with good constraints on the initial parton kinematics and flavour. Studies of momentum and angular correlations in photon-jet events can enable...
Jet quenching is one of the well-established signatures of the quark-gluon plasma produced in heavy ion collisions. Studies of energy balance for back-to-back hard probes, as well as medium-induced modifications to jet shapes and fragmentation functions, provide important experimental constraints for theoretical understanding of QGP properties. Using large sample of dijet events from 5.02 TeV...
The anomalous side-jump mechanism is a Lorentz invariant and angular momentum conserved approach to include the spin-orbital interactions in scatterings of chiral fermions [1]. In the present study, we incorporate for the first time this mechanism in a transport model that is based on the chiral kinetic equations. For a system of rotating and unpolarized quarks in a box, we find that the...
The aim of relativistic heavy-ion collisions is to investigate the properties of the Quark-Gluon Plasma (QGP) created at high-enough temperatures and/or densities. For this purpose, heavy-quarks, i.e. charm and beauty, are very useful probes for the characterization of the QGP. They are produced at the early stages of the collisions via initial hard scatterings and, therefore, they experience...
The study of charged-particle production in small systems as a function of event multiplicity has exhibited many of the features of collective behaviour found in heavy-ion collisions. Event multiplicity dependent studies may be subject to significant autocorrelation bias due to jet production. In order avoid these effects, a new multiplicity estimator has been proposed which is based on the...
Utilizing our developed relativistic viscous hydrodynamic code [1] to analysis of proton-lead and lead-lead collisions at the LHC [2], we investigate applicability of hydrodynamics, QGP bulk property and viscosities effects at hadronization process. Here we focus on one-particle distributions such as rapidity distributions and particle identified transverse momentum spectra and elliptic flows....
One of the remaining puzzles in heavy-ion physics is that strangeness enhancement - believed to be a signature of the Quark-Gluon Plasma - is not only observed in heavy-ion collisions, but also in high-multiplicity proton-proton and proton-nucleus collisions. Various phenomenological models have been developed to try to understand this, such as rope hadronisation (used in the Angantyr...
We investigate fluid-to-particle conversion using the usual Cooper-Frye approach but with more general local equilibrium distributions than the Boltzmann or Bose/Fermi distributions typically used. Even though we study ideal fluids (i.e., shear stress and bulk pressure are zero everywhere), we find a suppression of elliptic flow ($v_2$) at high transverse momenta ($p_T>1.5$ GeV/c), relative to...
We study the behaviour of the η′ around above the pseudocritical temperature by use of lattice QCD simulations with two families of dynamical quarks. Due to its anomalous component the η′ carries significant informations on the nature of the phase transition, and the role of the anomaly. We contrast and compare the results for the η′ with the behaviour of chiral observables as well as with...
Multiparticle correlations built from azimuthal angles whose distributions have been parametrized with the Fourier series expansion, depend generically on two distinct degrees of freedom: flow amplitudes $v_n$ and symmetry-planes $\Psi_n$. While analyses techniques for flow amplitudes $v_n$ have advanced over the past years, robust and unbiased techniques for analysing symmetry-planes...
The validity of the Statistical Hadronization Model (SHM) has been successfully tested to adequately reproduce hadronic particle abundances over nine orders of magnitude in high energy collisions of heavy ions. Assuming a thermally equilibrated system, experimental particle yields at RHIC and the LHC serve as an anchor for the determination of common freeze-out parameters in the QCD phase...
We will present a comprehensive study of chemical freeze-out parameters in high energy
collisions[1-3]. The experimental data of light flavor particles are used to obtain the freeze-out parameters using the statistical thermal model. Three different ensembles are used in this study: the grand canonical ensemble, the canonical ensemble with exact strangeness conservation, and the canonical...
The PHENIX experiment recently found a remarkably simple scaling law for the number of photons emitted in relativistic heavy ion collisions. When the direct-photon invariant yields are divided by $(dN_{ch}/d\eta)^{1.25}$, data from large systems falls onto a single curve in the low transverse momentum ("thermal") region. What is remarkable is that this is true if $dN_{ch}/d\eta$ is varied by...
Recent results at LHC and RHIC involving small collision systems have found evidence of collective flow behavior consistent with relativistic hydrodynamic expectations, which suggests the formation of tiny specks of quark-gluon plasma in these reactions. However, questions still remain about the nature of the matter formed in these minute systems. One of the main signatures of the quark-gluon...
Specific heat is a thermodynamic quantity that characterizes the equation of state of the system. For a system undergoing phase transition, the specific heat, $C_{V}$, is expected to diverge at the critical point. Temperature fluctuation of the system provides an estimation of $C_{V}$. The specific heat can be extracted from event-by-event temperature fluctuation. Thus the variation of thermal...
The electromagnetic (EMCal) and hadronic (HCal) calorimeters for the sPHENIX experiment will use about 100,000 Silicon Photo-Multipliers (SiPMs) as optical sensors (Hamamatsu S12572-33-015P). The effects of radiation damage in SiPMs from gamma rays has been measured and compared with the damage produced by neutrons. We designed and constructed an automated SiPM testing device that measures the...
The charm quarks are mainly produced by primordial hard scatterings in the early stage of the ultra-relativistic heavy-ion collisions. The produced charm quarks propagate through the dense QGP medium formed in such collisions and lose energy during their entire path of travel. The QGP is a statistical system of dynamic colour charges, it can also be characterised by stochastic...
The large Time Projection Chamber (TPC) is the main tracking and PID
device of the ALICE detector. It is currently being upgraded with a new
readout system, including new GEM-based Readout Chambers and new
front-end electronics. This will enable to operate the TPC in continuous mode,
recording the full minimum-bias interaction rate of 50 kHz in Pb-Pb, as
anticipated at the LHC in Run3...
The High Acceptance Di-Electron Spectrometer (HADES) is measuring properties of baryonic matter at moderate temperatures in A+A collisions at the SIS18 accelerator at GSI, Darmstadt. After a long shutdown of SIS18 to prepare for the future FAIR facility, beamtimes have been resumed within the FAIR Phase-0 program in March 2019.
Meanwhile, the HADES experiment has undergone several upgrades....
Neutral mesons and jets are good probes to study particle production mechanisms and jet phenomena in various collision systems, providing comparisons to model calculations and constraining coefficients of hot QCD matter. Recent measurements of ALICE in pp collisions show a modification of the $\eta/\pi^{0}$ ratio for the neutral meson production in jets with respect to the inclusive...
In order to study the high-density nuclear equation-of-state in collisions between gold nuclei at Nuclotron beam energies (2– 4.5A GeV), the existing BM@N experiment at JINR in Dubna has to be substantially upgraded. The measurement of high-multiplicity events at reaction rates up to 50 kHz requires the installation of four new tracking stations equipped with double-sided micro-strip silicon...
In order to measure the orientation of the spectator reaction plane, the CMS Zero-Degree Calorimeters (ZDCs) are augmented with two 4x4 hodoscopes of quartz tiles, called the Spectator Reaction Plane Detectors. To reduce electronic noise the signals are digitized in the tunnel, very close to the detectors, which sit at zero degrees, 140m from the interaction point. The performance of the...
We present measurements of the second-order off-diagonal cumulants of net-charge, net-proton, and net-kaon multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}} =$ 7.7-200 GeV. We focus on the pseudorapidity window and centrality dependence of these cumulants. We compare our results with the hadron resonance gas (HRG) and UrQMD calculations. The energy dependence of the second order...
Measurements of the correlated fluctuations of the amplitudes of two different flow harmonics have been shown to be more sensitive to the properties of the Quark-Gluon Plasma created in ultrarelativistic heavy-ion collisions than the flow harmonics taken individually. In particular, their computation have given constraints to the details of the temperature dependence of shear viscosity to...
Classical and quantum Tsallis distributions have been widely used in many branches of natural sciences. But, the quantum field theory of the Tsallis distributions is relatively a less explored arena. In the article arXiv:1906.02893v2 [hep-ph], we derived the expressions for the thermal two-point functions for the Tsallis statistics with the help of the corresponding statistical mechanical...
Sexaquarks are a hypothetical low mass, small radius uuddss dibaryon which has been proposed recently and especially as a candidate for Dark Matter [1]. The low mass region below 2 GeV escapes upper limits set from experiments which have searched for the uuddss dibaryon and did not find it [1].
Depending on its mass, such state may be absolutely stable or almost stable with decay rate of...
Due to the relative motion of the charged heavy-ions in heavy-ion-collision experiments, a high magnetic field is produced. The initial magnitude of this magnetic field can be very high at RHIC and LHC energies at the time of the collision and then it decreases very fast. The presence of an external anisotropic field in the medium subsequently requires modification of the present theoretical...
The recent detection of gravitational wave signal from binary
compact star merger has set a strong constraint on tidal defomability,
which motivated a large amount of studies about the equation of state.
But the tidal deformability of compact star depends not only on the
equation of state, but also on the spin and magnetic field of the star.
In this study, we calculated for the first...
In the past several years there has been increasing interest in the chirality imbalance $n_5$, which is the difference between right- and left-handed fermions. The chirality imbalance is expected to be produced from the Adler-Bell-Jackiw anomaly(ABJ-anomaly) and plays a key role to understand anomalous transport phenomena in the hot/dense quark matter or the Dirac/Weyl semimetals under the...
During the second LHC shutdown (LS2) the Inner Tracking System (ITS) of ALICE will be upgraded by replacing the current ITS with seven layers of CMOS Monolithic Active Pixel Sensors (MAPS). However, the latest innovations in the silicon imaging technology allow for the construction of large, ultra thin silicon wafers which can further improve the capabilities of the ALICE tracker. A proposal...
The origin of long-range collective azimuthal correlations in small-system collisions is an area of intense research in the heavy ion community. To disentangle between collectivity associated with initial-state intrinsic momentum anisotropy and the collectivity arising as a final-state response to the collision geometry, we studied the development of collectivity in 5.02 TeV and 0.2 TeV $p$+Pb...
Complementary to jet reconstruction, two-particle correlations in $\Delta\eta$ and $\Delta\varphi$ are used to study jets, in particular their particle composition. While in Pb-Pb collisions this is done as means for the characterization of the Quark-Glon Plasma, pp collisions serve as reference and also allow for a deeper study of particle production mechanisms. Recent ALICE results on the...
The LIDO partonic transport model is used to study the evolution of hard partons inside the quark-gluon plasma produced in heavy-ion collisions.
The energy loss model includes scatterings between hard partons and the medium as well as inelastic (bremsstrahlung) processes.
Importantly, the model takes into account the finite formation time of parton bremsstrahlung, an essential ingredient...
We apply the iterative Bayesian unfolding method provided by RooUnfold package in the non-binomial efficiency correction problem for higher moments. We study the non-binomial efficiency distribution such as beta-binomial and hypergeometric distributions in this work. We also consider the efficiency with multiplicity dependence and the effect of track merging, which will lead to non-binomial...
Comprehensive understanding of medium-induced radiative energy loss is of a paramount importance in describing observed jet quenching in heavy-ion collisions. In this work, we calculate the medium-modified gluon splitting rates for different profiles of the expanding partonic medium, namely profiles for static, exponential, and Bjorken expanding medium. In the presented study, the...
While at at zero baryon chemical potentials one expects a minimum in the shear viscosity over entropy density and a maximum in the bulk viscosity to entropy density ratio, the exact values where these characteristic temperatures occur has not yet been determined from first principle Lattice QCD calculations and may occur anywhere within the cross-over regime of the phase transition. However,...
Heavy-ion collisions produce asymmetric pressure gradients which convert via interactions the initial spatial asymmetry into an anisotropy in final state momentum space, a phenomenon referred to as anisotropic flow. Anisotropic flow is characterized using the harmonic coefficients $v_{\rm n}$ in a Fourier decomposition of the azimuthal distribution of produced particles relative to the...
The recent detection of a binary neutron star merger using gravitational waves and electromagnetic signals marked the dawn of the multi-messenger astronomy era. Such events are expected to provide key information about the properties of matter at extreme densities and temperatures and, for many years, it was assumed that this system could be reasonably described as an ideal (i.e. inviscid)...
It’s believed that the properties of quark-gluon-plasma (QGP) can be studied through measurements of the jet quenching phenomenon. More specifically, observation of jet substructure variables may reveal the microscopic properties of the QGP.
Recently the modification of groomed jet observables was studied in heavy-ion collisions [1]. In addition, the Lund radiation plane was introduced to...
The chiral vortical effect (CVE) is believed to be intrinsically related to the anomalies of the axial current and the topological properties of the system. It was suggested that the CVE can be generalized to systems of higher-spin particles and, particularly, to photons. However, there is no local gauge invariant definition of photonic helicity current. This problem can be overcome with an...
ATLAS measurements of flow harmonics ($v_{n}$) and their fluctuations in Pb+Pb and Xe+Xe collisions covering a wide range of transverse momenta, pseudorapidity and collision centrality are presented. The $v_{n}$ are measured up to $n=7$ using the two-particle correlations, multi-particle cumulants and scalar product methods.The $v_{n}$ for $n$=2-7 is obtained with various correlation methods,...
Measurements of long-range, collective azimuthal correlations involving heavy-flavor quarks provide a powerful tool for unraveling the origin of the collectivity observed in small collision systems. In particular, these measurements are sensitive to the early stages of the collisions. As compared to those for light flavor hadrons, large azimuthal anisotropy signals have been observed by CMS...
The first evidence of jet quenching was observed at RHIC via suppression of single high $p_T$ hadron
$R_{AA}$ and the disappearance of the awayside jet peak in two-particle correlations. Hadron
$R_{AA}$ and two particle correlations continue to be useful probes of the QGP in heavy ion collisions,
since the particles involved are fragments of the jets produced in the initial hard scattering....
In ultra-relativistic heavy-ion collisions, one expects copious rates of $\gamma+\gamma$ processes through the interaction of the large electromagnetic fields of the nuclei, which can produce new particles (e.g. leptons) or even lead to light-by-light scattering via loop diagrams. The latter process is a notable prediction of QED and was only recently observed by ATLAS using the full 2018...
ATLAS measurements of azimuthal anisotropy of heavy flavor mesons in the small systems is presented. A template fit method is used to subtract non-flow contributions using simultaneous fit to low and high charged-particle multiplicity samples. The heavy flavor flow in $p$+Pb is studied using multiple probes, including prompt $D^{0}$ mesons, J/$\psi$, and muons from semi-leptonic decays of...
Jet quenching refers to the energy loss of partons due to interactions with the Quark Gluon Plasma (QGP) in relativistic heavy-ion collisions. It generally modifies measured jet spectra as well as substructure, including the fragmentation pattern and radial distribution of transverse momentum ($\it{p}_{T}$) inside the jet relative to jets in vacuum. In this talk, we report measurements of...
Studies of longitudinal de-correlation of anisotropic flow provide unique constraints on the initial conditions and dynamical evolution of the quark-gluon-plasma in heavy-ion collisions. With data collected by the STAR experiment at RHIC, the factorization ratio for flow harmonics, $r_n(\eta^a, \eta^b) (n = 2, 3)$, are obtained over a wide $\eta$ range for 27 and 54.4 GeV Au+Au collisions as a...
Ultra-relativistic heavy ion collisions are expected to produce some of the strongest magnetic fields ($10^{13}−10^{16}$ Tesla) in the Universe [1]. Recently, there has been intense interest in the magnetic fields produced by heavy ion collisions and their possible observational impacts through phenomena like the Chiral Magnetic Effect. The initial strong electromagnetic fields produced in...
We report the first direct measurement of the dead-cone effect at colliders, using iterative jet declustering techniques in pp collisions at $\sqrt{s}=13$ TeV. The procedure detailed in, exposes the splittings of D mesons in the jet shower, by iteratively declustering the angular ordered C/A tree. The splitting history of the D meson initiated jet is mapped onto the Lund plane, where...
To study the microscopic structure of quark-gluon plasma, data from hadronic collisions must be confronted with models that go beyond fluid dynamics. Here, I describe a study of a kinetic theory model that encompasses fluid dynamics but contains also particle-like excitations in a boost invariant setting with no symmetries in the transverse plane. The kinetic theory results are compared to...
In heavy-ion collisions, it is well-established that geometrical shapes of the initial density distribution in transverse plane are responsible for the observed harmonic flow, through the hydrodynamic response of a set of modes. In particular, elliptic flow $V_2$ is linearly proportional to initial eccentricity $\mathcal{E}_2$.
In this work, we generalize the framework to study...
We present the first study quantifying the sensitivity of hadron and photon observables to the early-time evolution in heavy-ion collisions which implements a realistic pre-equilibrium stage with effective QCD kinetic theory [1, 2] and a state-of-the-art hybrid (IP-Glasma + MUSIC + UrQMD) framework [3]. We calculate photon emission from the pre-equilibrium phase by folding the system's energy...
Photo-produced vector mesons in ultra-peripheral Pb-Pb collisions at forward rapidity are sensitive to the small-x parton distribution functions (nPDFs) in the target nucleus. In pPb collisions, measurements of the Z production in forward (pPb) and backward (Pbp) configuration are also sensitive to the nPDFs in another kinematic domain, both probes allowing to study in a complementary fashion...
Quantifying the differences between nuclear and hadronic collisions, phenomenologically known as medium modification due to multiple scatterings between the hard probe and medium, can provide a solid baseline for unambiguous identification of the medium fundamental property. In this talk, we consider parton propagation in cold nuclear matter within the framework of high-twist expansion, which...
We present a comprehensive measurement of the transversal momentum ($p_T$) and multiplicity ($N_{ch}$) dependence of azimuthal harmonics $v_2$ and $v_3$ in RHIC small system scan at $\sqrt{s_{NN}}=200$ GeV. This measurement contains several new results and important improvements: 1) previous results on $v_2$ in p+Au and d+Au collisions are now expanded to include $^3$He+Au collisions, as well...
Factorization breaking of flow coefficients is actively studied to understand longitudinal dynamics of the quark-gluon plasma produced in high-energy nuclear collisions, yet no hydrodynamic models have successfully described the centrality dependence of the factorization breaking in various collisions systems. In this study, we reproduce the centrality dependence of rapidity decorrelation in...
Cross sections for photon production in hadronic scattering processes have been calculated according to an effective chiral field theory. For $\pi + \rho \to \pi + \gamma$ and $\pi + \pi \to \rho + \gamma$ processes, these cross sections have been implemented into a novel hadronic transport approach (SMASH), which is suitable for collisions at low and intermediate energies. The...
Anisotropic flow fluctuations can be used to probe the properties and evolution of the system created in heavy-ion collisions. In this talk, we present the first $p_{\rm T}$-differential measurements of the first and second order moments of $v_{\rm 2}$ probability density function (PDF), extracted from a comprehensive set of light-flavor hadrons. In addition, we also present higher order...
We present a systematic study of the hydrodynamic medium response to jet shower propagation, based on a strongly-coupled description of the Quark-Gluon Plasma (QGP). A causal formulation for the space-time profile of energy-momentum source terms is incorporated with a multi-stage jet evolution and (3+1)-D viscous hydrodynamics within the JETSCAPE 2.0 framework. In this work, we employ a causal...
Quarkonium production measurements represent a key probe to investigate the space-time properties of the Quark-Gluon Plasma (QGP) created in heavy-ion collisions. Measurements in small systems, namely pA and proton-proton (pp), are crucial in order to interpret correctly results in heavy-ion collisions. Potential initial-state effects can be constrained through the measurement of the nuclear...
It is the aim of the RHIC BES program and the future FAIR and NICA facilities to produce compressed baryonic matter. In such experiments, strong gradients in baryon density are expected, and therefore the diffusion of baryon number could play a major role in the description of the fireball. The constituents of the produced matter carry a multitude of conserved charges, namely the baryon...
The particular azimuthal angular correlation between a heavy meson and a light hadron has first been measured at the LHC recently. In this two particle correlation method, the experimental results show that the elliptic flows for heavy-flavor mesons (J/psi and D^0) are almost as large as those for light hadrons. We investigate the angular correlation between a heavy quarkonium and a charged...
Charm quarks are a powerful probe of the Quark-Gluon Plasma (QGP) formed in
high- energy heavy-ion collisions. Produced in hard scattering processes on a
timescale shorter than the QGP formation time, they experience the whole evolution
of the medium interacting with its constituents. The measurements of charm-hadron
production allows testing the mechanisms of in-medium parton energy...
Recently there have been rapidly growing interests in understanding the properties and phase structures of matter under extreme fields like magnetic field or global rotation. Examples of such physical systems come from a variety of different areas, such as the hot quark-gluon plasma in peripheral heavy ion collisions, dense nuclear matter in rapidly spinning neutron stars, lattice gauge theory...
One of the key goals of nuclear collision experiments is to map the phase diagram of strongly interacting matter. At LHC energies there would be, for vanishing light quark masses, a temperature-driven genuine phase transition of second order between the hadron gas and the quark-gluon plasma. For realistic quark masses, however, this transition becomes a smooth cross over. Nevertheless, due to...
The ALICE Collaboration reports a search for jet quenching effects in high multiplicity pp collisions at $\sqrt{s}$ = 13 TeV, utilizing the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum charged-hadron trigger. The multiplicity is measured using forward scintillation detectors that are separated in phase-space from the central region where the...
The enhancements of D_s/D^0 and Lambda_c/D^0 ratios in heavy-ion collisions as recently measured at RHIC and the LHC have posed formidable challenges for
theoretical models. We address these puzzles by developing a theoretically
controlled hadronization framework of heavy quarks that conserves 4-momentum and
recovers thermal and chemical equilibrium limits [1]. In particular, we implement...
Charged particles in small collision systems such as $pp$ and $p$+Pb have been observed to have significant azimuthal modulations of their momenta, commonly interpreted as flow, up to a transverse momentum of $p_{T} \approx 10$~GeV. In large collision systems such as Pb+Pb, lower but non-zero flow coefficients at higher $p_{T}$ ($> 10$~GeV) are usually understood to reflect jet quenching, and...
Higher-order cumulants of conserved quantities (B, Q, S) are sensitive observables to study the QCD phase structures, nature of quark-hadron phase transition and freeze-out dynamics.
In this talk, we will present new measurements of sixth to second-order cumulant ratios (C6/C2) of net-proton distributions in Au+Au collisions at sNN =54.4 and 200 GeV, as well as cumulants up to the...
We explore the perspectives of machine learning techniques in the context of quantum field theories. In particular, we discuss two-dimensional complex scalar field theory at nonzero temperature and chemical potential – a theory with a nontrivial phase diagram. A neural network is successfully trained to recognize the different phases of this system and to predict the value of various...
The aim of the NA61/SHINE strong interaction programme is to explore the phase diagram of strongly interacting matter. The main physics goals are the study of the onset of deconfinement and the search for the critical point of strongly interacting matter. These goals are pursued by performing a beam momentum (13A - 158A GeV/c) and system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb) scan. This...
The collective flow and the possible formation of the Quark-Gluon Plasma (QGP) in the small colliding systems are hot research topics in the heavy-ion community. Recently, ALICE, ATLAS and CMS collaborations have measured the elliptic flow and the related number of constituent quark (NCQ) scaling of identified hadrons in p+Pb collisions at $\sqrt{s}$ = 5.02 TeV, which are important...
An efficient way to study the QCD phase diagram at small finite density
is to extrapolate thermodynamical observables from imaginary chemical
potential. The phase diagram features a crossover line starting from the
transition temperature already determined at zero chemical potential. In
this talk we focus on the Taylor expansion of this line up to $\mu^4$
contributions. We present the...
In hadronic collisions, beauty quarks are produced in hard scattering processes with large momentum transfer.Their production provides a very important test of perturbative QCD calculations in pp collisions. In heavy-ion collisions, the measurement of beauty hadron production is a unique tool to investigate the properties of the Quark-Gluon Plasma. In particular, beauty quarks, being four...
The physics program of the Compressed Baryonic Matter (CBM) experiment at FAIR is focused on the measurement of properties of nuclear matter at high net-baryonic density. This experiment will offer the possibility to find signatures of discontinuous transition from QGP to hadronic phase and the QCD critical point where the first order phase transition ends. In the search of the QCD phase...
In the plane of temperature and chemical potential, QCD may exhibit a Critical End Point (CEP). if a region with spatially inhomogeneous condensates exists, there may also be a Lifshitz Regime, either instead of, or in addition to, a CEP. We study the Lifshitz Regime using both a large N expansion and using numerical simulations at small N. Experimentally, we contrast the fluctuations in...
We study a range of collision systems involving deformed ions and compare the elliptic and triangular flow harmonics produced in a hydrodynamics scenario versus a color glass condensate (CGC) scenario. For the hydrodynamics scenario, we generate initial conditions using TRENTO and work within a linear response approximation to obtain the final flow harmonics. For the CGC scenario, we use the...
Recent measurements of small system collisions, p+p and p+A, show signals which, in A+A collisions, had been attributed to the formation of a strongly interacting medium. These notably include flow-like correlations. However, so far no clear demonstration of jet energy losses in small system collisions have been observed.
In this talk, we will present correlations of mid-rapidity charged...
For the discovery of the QCD critical point it is crucial to develop dynamical models of the fluctuations of the net-baryon number that can be embedded in simulations of heavy-ion collisions.
In this talk we present the implementation of net-baryon number fluctuations near the critical point in an expanding system. We include the coupling to the fluctuations of energy density and momentum...
Heavy flavor physics in high-energy heavy-ion collisions is a promising and active area to study the `` jet quenching " effects both at the RHIC and the LHC. The recent reported $D^0$ meson radial profiles in jets measured by CMS collaboration provide new experimental constraints on the mechanisms of heavy flavor production in proton-proton collisions and give new insights into the in-medium...
Long-distance properties of QCD are non-perturbative in nature. Lattice computations provide a reliable tool for extracting such information for correlation functions in the space-like domain of momenta, for example for screening phenomena. However, the approach to equilibrium of QCD matter requires knowledge of correlation functions in the time-like domain.
Analytic continuation of...
Multi-particle azimuthal cumulants are measured as a function of centrality and transverse momentum in 5.02 TeV Pb+Pb collisions. These cumulants provide information on the event-by-event fluctuations of harmonic flow coefficients $v_{n}$ and correlated fluctuations between two harmonics $v_{n}$ and $v_{m}$.
For the first time, a non-zero four-particle cumulant is observed for dipolar flow,...
The experimentally observed dissociation and regeneration of bound quarkonium states in heavy-ion collisions provide a powerful tool to probe the dynamics of the hot, dense plasma. These measurements are sensitive to the effects of color screening, color recombination, and possibly to other, new phenomena affecting dynamics of heavy quarks in the QCD medium. In the large-statistics Run 2...
Theoretical considerations suggest the chiral magnetic effect (CME) and chiral magnetic wave (CMW) are reflected in a charge separation with respect to the event plane in heavy-ion collisions. Although considerable experimental efforts have been expended to investigate the existence of such phenomena, in recent years, evidence remains inconclusive because observables sensitive to these...
The thermalized QCD matter formed in heavy-ion collisions is tilted in the reaction plane as a function of rapidity, while the production profile of partons from hard scatterings is symmetric in rapidity [1]. This leads to a rapidity-odd directed flow (v1) for high-pT hadrons and can provide valuable constraints on the initial longitudinal distribution of the fireball as well as the path...
As a conserved quantity in the evolution of the quark-gluon plasma (QGP) created in heavy-ion collisions, the total angular momentum consists of two sectors: the orbital angular momentum (OAM) caused by kinetic motion, and the intrinsic spin angular momentum of quarks and gluons. In a heavy-ion collision event, the system starts with finite OAM but un-polarized spin density (unless prepared...
Heavy quarks are produced at the first instant of a nucleus-nucleus collision and therefore
are an important tool to study the subsequent high energy-density medium formed in
relativistic heavy-ion collisions. Over the last few decades major efforts have been
undertaken in order to understand the properties of the Quark-Gluon Plasma (QGP) using
quarkonia. The extent of medium...
We present two approaches to handle the dominant elliptic flow ($v_2$) background in the observable, $\Delta\gamma_{112}$ (charge separation across second-order event plane), sensitive to the chiral magnetic effect (CME).
In the first approach, we present the $\Delta\gamma_{112}$ and $\Delta\gamma_{123}$ measurements in U+U and Au+Au collisions. While hydrodynamic simulations including...
Nuclear structure functions and parton Wigner distributions of protons and nuclei are principal components of QCD phenomenology. Their first principle computation is an outstanding problem in QCD, because they involve non-perturbative nucleon/nuclear matrix elements of electromagnetic currents that are light-like separated in Minkowskian spacetime. Real-time correlation functions are a...
One of the most important objectives of Beam energy scan (BES) program at the Relativistic Heavy ion collider (RHIC) is to search for the critical point in the QCD matter via performing nucleus-nucleus collisions with wide collision energies (7.7 - 200 GeV). At such energies, the produced quark-gluon plasma (QGP) matter has sizable net baryon density at the central rapidity region due to...
We will present recent results on thermal modifications of heavy quark spectral functions and transport properties based on continuum extrapolated charmonium and bottomonium correlation functions in pure SU(3) plasma, extending the previous study in the pseudoscalar channel to the vector channel. Using the gradient flow technique for the color-electric field correlator on large and fine...
Experimental searches for CME in heavy ion collisions have been going on for a decade, and so far there is no conclusive evidence for its existence. Recently, the Signed Balance Function (SBF), based on the idea of examining the momentum ordering of charged pairs along the in- and out-of-plane directions, has been proposed as a probe of Chiral Magnetic Effect (CME) [1]. In this approach a...
The covariant Wigner function formalism is a powerful and systematic quantum kinetic approach. In this talk, we will discuss how the chirality and spin transport in relativistic plasma can be described from Wigner function approach. It provides very natural and systematic method to describe the chiral effects and spin effects in heavy ion collisions. We find that the massless fermion systems...
An outstanding puzzle in the field is the mechanism that generates collective motion of heavy quarks (charm and bottom) in large collision systems. The measured azimuthal anisotropies of electrons from heavy quarks closely resemble those of light quarks, despite the enormous differences in quark mass. In order to further understand the quark mass dependence of the flow, we have separated the...
Heavy quarkonia are useful probes of the quark-gluon plasma, where quarkonium dissociation is expected at high enough temperatures. Indeed, such a suppression is clearly present in the latest STAR measurements of $J/\Psi$ production in Au+Au collisions. The suppression is observed to have little dependence on $p_{T}$, although cold nuclear matter effects, such as shadowing, anti-shadowing,...
A primary goal in heavy-ion collisions is to learn about non-equilibrium properties of the quark-gluon plasma (QGP), such as the size of its thermalization timescale and the values of its transport coefficients. Hard experimental probes like jets and heavy quarks, as well as photons [1], give direct access to these non-equilibrium properties. However, theoretical challenges have hindered...
Nuclear modification of charmonium in small systems is thought to be caused by a combination of initial-state effects in the charm quark production, such as depletion from gluon shadowing and Cronin enhancement, and final-state breakup through comoving particles. The timescale of a charmonium state to neutralize with respect to the duration of the charmonium crossing the nuclear media may also...
In ultrarelativistic heavy-ion collisions, a very strong (on the order of $10^{16}~\mathrm{Tesla}$) and transient (lifetime on the order of $10^{-1}~\mathrm{fm/c}$) electromagnetic (EM) field is expected to be generated inside the medium formed in the collision. This EM field, generated by the collision participants and spectators, is predicted to produce a difference in the $v_n$ harmonics...
Relativistic heavy-ion experiments have observed similar quenching effects for (prompt) $D$ mesons compared to charged hadrons for transverse momenta larger than 6-8 GeV, which remains a mystery since heavy quarks typically lose less energies in quark-gluon plasma than light quarks and gluons. Recent measurements of the nuclear modification factors of $B$ mesons and $B$-decayed $D$ mesons by...
The interplay between the chiral magnetic effect and the chiral separation effect can lead to a collective excitation, a phenomenon called Chiral Magnetic Wave (CMW). Previous measurement of a positive slope for the charge asymmetry ($A_{\rm ch}$) dependence of the $\pi^{+}$ and $\pi^{-}$ flow difference $\Delta v_{2}(A_{\rm ch})\equiv v_{2}^{\pi^{-}}(A_{\rm ch}) - v_{2}^{\pi^{+}}(A_{\rm...
The study of the QCD interaction at high temperature in the heavy quark (HQ) sector has attracted a wide interest in the last decade. The theoretical efforts to build realistic phenomenological models able to predict the main observables for D mesons, $R_{AA}$ and $v_2$, has lead to a first estimate of the Ds space diffusion of charm quarks. This has been a successful program that has allowed...
New results on the production of light nuclei, including deuterons, tritons,
$^{3}\rm{He}$, $^{4}\rm{He}$ and the corresponding anti-nuclei, in Pb-Pb collisions
at $\sqrt{s_{\rm NN}}$ = 2.76 TeV and $\sqrt{s_{\rm NN}}$ = 5.02 TeV will be presented
and compared with theoretical predictions to provide insight into their production
mechanisms in heavy-ion collisions. Those results will be...
The production cross-sections are reported for the $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ mesons in pp and PbPb collisions at 5.02 TeV, as functions of transverse momentum and rapidity. The dependence of the yield on the event activity and collision centrality is also presented for PbPb collisions. A comparison with the 2.76 TeV data in order to assess the energy dependence of the...
Anisotropic flow provides valuable information on the key properties and the evolution of the matter created in heavy-ion collisions. In this talk, we present the elliptic and triangular flow of inclusive and identified particles measured in Xe-Xe collisions at $\sqrt{s_{\rm NN}} = 5.44$ TeV recorded by the ALICE detector. The measurements are reported for a wide range of particle transverse...
A wide variety of recent measurements from small systems indicate that there are collective flow phenomena in these systems, which are well described by hydrodynamics. However, it is widely understood that all flow measurements are affected by non-flow correlations. In order to disentangle the genuine hydrodynamical flow from other contributions, we have systematically studied the $v_2$ as a...
The Beam Energy Scan program (BES) at the Relativistic Heavy Ion Collider (RHIC) is dedicated to exploring the Quantum Chromodynamics (QCD) phase diagram and search for the critical point of the QCD phase transition. The results from the BES phase I program show hints of a first-order phase transition in the QCD phase diagram and the turn-off of the characteristic signatures of the quark gluon...
Nuclear parton distribution functions (nPDFs) of quarks and antiquarks affect the production of electroweak bosons in proton-lead (pPb) collisions. In this presentation, the measurements of the neutral Drell-Yan (DY) process and of the W bosons are presented in pPb collision at the center of mass energy of 8.16 TeV with the CMS detector. The rapidity dependence of these processes is...
Short-lived hadronic resonances are used to study different aspects of particle production
and collision dynamics in pp, p—A and relativistic heavy-ion collisions. The yields of
resonances are sensitive to the competing processes of hadron rescattering and regeneration,
thus making these particles unique probes of the properties of the late hadronic phase.
Measurements of resonances...
Heavy quarks are unique tools to investigate the properties of the Quark-Gluon Plasma (QGP) formed in ultra-relativistic heavy-ion collisions. Due to the large masses, heavy quarks
are produced in hard scattering processes on timescales shorter than the QGP formation time, thus they experience the entire evolution of the medium interacting with its constituents.
The hot QCD matter is...
The Multi-Purpose Detector is under construction at the Joint Institute for Nuclear Research, as part of the NICA Accelerator Complex. It aims to study the phase diagram of QCD matter at maximum baryonic density, determine the nature of the phase transition between the deconfined and hadronic matter and search for the critical point in the diagram. The current status of the construction of MPD...
We present a formulation of the initial state of heavy ion collisions that generalizes the 2+1D boost invariant IP-Glasma [1] to 3+1D through JIMWLK rapidity evolution of the pre-collision Wilson lines. The rapidity dependence introduced by the JIMWLK evolution means that 1) the system no longer trivially satisfies Gauss’ law at the initial time and 2) the form of the 2+1D initial gauge fields...
High energy jets, evolving from a single parton, produced with transverse momentum up to a TeV, have a variety of scale dependent interactions with the QGP. The mass of heavy-quarks introduce another scale within this evolution. Modeling both the heavy quark shower and the fluid dynamical medium event by event, we demonstrate that in the high virtuality portion of a jet, where the dead-cone...
We carry out a principal component analysis of fluctuations in a hydrodynamic simulation of heavy-ion collisions, and compare with experimental data from the CMS collaboration. The principal components of anisotropic flow reproduce the trends seen in data, but multiplicity fluctuations show an interesting difference in transverse momentum dependence. We checked this is also the case for other...
The Compressed Baryonic Matter experiment (CBM) at FAIR aims to study the area of the QCD phase diagram at high net baryon densities and moderate temperatures using heavy-ion collisions. The FAIR accelerator will provide high-intensity heavy-ion beams up to Au ions in the energy range 2-11 GeV per nucleon. In order to achieve it's physics goals and to perform multi-differential measurements of...
Using deep neural network, the nature of the QCD transition can be identified from only the final-state pion spectra from hybrid model simulations of heavy-ion collisions. Within this hybrid model, a viscous hydrodynamic model is coupled to a hadronic cascade “after-burner”. Two different types of equations of state (EoS) of the medium are used in the hydrodynamic evolution. The resulting...
The largely unknown parton distribution functions of nuclei and the similarities observed between high-multiplicity pp and pPb events compared to PbPb, often described by means of hydrodynamics, are the main motivations for an extended pPb data taking program during LHC Run 3 and Run 4. The future increase in luminosity combined with the LHCb unique detector capabilities will allow to perform...
Previous measurements in small systems indicate that the modifications to jets relative to p+p collisions is small. However, looking at more differential measurements may reveal if any modifications do exist. In particular, we compare $\pi^0$-hadron correlations measured with PHENIX in small systems to those observed in p+p collisions to probe any initial state effects. Several systematic...
The production of heavy quarkonium in heavy ion collisions has been used as an important probe of the quark-gluon plasma. The initial insight was that due to the plasma screening effect, the color attraction between the heavy quark-antiquark pair is significantly suppressed at high temperature and thus no bound states can exist, i.e., they “melt”. In addition to the screening of the color...
We study the heavy-quark momentum diffusion coefficient in far from equilibrium gluon plasma in a self-similar regime using real-time lattice techniques. We use 3 methods for the extraction: an unequal time electric field 2-point correlator integrated over the time difference, hard loop (HTL) perturbation theory and a kinetic theory formula, both using our recently acquired data on the gluon...
We present state-of-the-art constraints on the properties of the quark-gluon plasma by performing a comprehensive Bayesian model-to-data comparison of heavy-ion measurements. Soft observables from both RHIC and the LHC are combined into a global Bayesian analysis, enabling us to obtain more reliable constraints on the transport coefficients of QCD, in particular for the temperature dependence...
The Compact Muon Solenoid (CMS) detector at the CERN Large Hadron Collider (LHC) is undergoing an extensive Phase II upgrade program to prepare for the challenging conditions of the High-Luminosity LHC (HL-LHC). A new timing layer is designed to measure minimum ionizing particles (MIPs) with a time resolution of ~30 ps and hermetic coverage up to a pseudo-rapidity of $|\eta|$=3. The precision...
Measurements of nuclear modification factors (RAA) and elliptic flow (v2) for open heavy flavor hadrons are essential probes of the Quark Gluon Plasma produced in heavy-ion collisions. Single electrons from semi-leptonic decays are an excellent channel to study open heavy flavor due to their large branching fractions and triggering possibilities. Additionally, semi-leptonic c-hadron decays can...
The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will measure a suite of unique jet and Upsilon observables with unprecedented statistics and kinematic reach at RHIC energies. A MAPS-based vertex detector upgrade to sPHENIX, the MVTX, will provide a precise determination of the impact parameter of tracks relative to the primary vertex in high multiplicity heavy ion...
Based on Refs. [1] and [2], we discuss the new constraints on gluon parton distribution function (PDF) in lead nucleus, derivable with the Hessian PDF reweighting method from the 5.02 TeV p+Pb measurements of CMS dijet [3] and LHCb $D^0$-meson [4] nuclear modification ratios. The impact is found to be significant, placing stringent constraints in the mid- and previously unconstrained small-$x$...
The production of light neutral mesons in AA collisions probes the physics of the Quark-Gluon Plasma (QGP), which is formed in heavy-ion collisions at the LHC. More specifically, the centrality dependent neutral meson production in AA collisions compared to its production in minimum-bias pp collisions, known as nuclear modification factor, provides information on the energy loss of partons...
The heavy-flavor transport coefficients contain important information on the strong interaction at finite temperatures. Extraction of these numbers from experimental data requires dynamical modeling of heavy-flavor transport that is coupled to a realistic medium evolution. Furthermore, meaningful extractions necessitate both a faithful implementation of the physical inputs to be tested and the...
Equilibration of highly excited baryon-rich matter is studied within the
microscopic model calculations in A+A collisions at energies of BES, FAIR
and NICA. It is shown that the system evolution from the very beginning
of the collision can be approximated by relativistic hydrodynamics, although
the hot and dense nuclear matter is not in local equilibrium yet.
During the evolution of the...
It is largely acknowledged that heavy flavor probes are sensitive to the properties of the quark gluon plasma and as such they are often considered an important tool for the plasma tomography studies. In the past several years there has been an astounding amount of work aimed at understanding the heavy quarks coupling with the medium. Nevertheless, the longitudinal dependence of common...
We present results on azimuthally-integrated and azimuthally-dependent analyses of identical pion intensity interferometry (HBT) studied in collisions of Au+Au at $\sqrt{s_{NN}}=2.4$ GeV. The data are taken with the HADES spectrometer at SIS18/GSI Darmstadt. We study the dependence of the space-time extent of the pion emitting source on the pair transverse momentum and on the collision...
The ALICE experiment at CERN is undergoing a major upgrade during the Long Shutdown 2 (LS2) of the LHC during 2019-2020. The key elements regarding the central barrel are the installation of a new Inner Tracking System (ITS) and the upgrade of the large Time Projection Chamber (TPC).
The TPC, the main tracking and PID device of ALICE, is currently being upgraded with a new readout system,...
We present a new method to calculate the final decay spectrum of direct resonance decays directly from hydrodynamic fields on a freeze-out surface. The method is based on identifying components of the final particle spectrum that transform in an irreducible way under rotations in the fluid-restframe. Corresponding distribution functions can be pre-computed including all resonance decays. Just...
The applicability of fluid-dynamical models in the extreme conditions produced in heavy ion collisions has not yet been properly understood from a theoretical point of view. This happens mostly because the derivation of hydrodynamics from microscopic theory often relies on the assumption that the system is sufficiently close to local equilibrium -- something difficult to justify in the rapidly...
Jets can be used to study in-medium modifications of the parton shower and the energy loss mechanisms in heavy ion collisions. Several recent works at LHC have hinted that quark and gluon fractions in measured jets may be modified in QGP due to quenching. Jet charge is defined as the momentum-weighted sum of charges of particles inside a jet. It is sensitive to the charge of the initiating...
Recent ALICE measurements of jet splittings in Pb—Pb and pp collisions using the new 2018 data at $\sqrt{s}_{\rm NN}$ = 5.02 TeV will be shown. These measurements scan the phase space of emissions inside of the jet in search of a medium-induced signal, which are expected to emerge at different scales and include effects such as multiple soft-radiation, single hard emissions, and color...
In high energy nuclear collisions, light nuclei can be regarded as a cluster of baryons and their yields are sensitive to the baryon density fluctuations. Thus, the production of light nuclei can be used to study the QCD phase transition, at which the baryon density fluctuation will be enhanced. For example, the ratio of proton ($N(p)$) and triton ($N(t)$) to deuteron ($N(d)$) yields, which is...
The ATLAS collaboration has recently shown that anisotropic flow exhibits a strong centrality dependence in ultracentral collisions [arXiv:1904.04808]. In particular, the 4-particle cumulant of elliptic flow changes sign, and the centrality at which this change of sign occurs depends on the observable which is used to determine the centrality. We show that these features are universal...
We propose and develop a new formalism that generalizes the Color Glass Condensate approach to high energy scattering by including both small and large $x$ gluons in the wave function of a target proton or nucleus. This allows one to treat particle production at both low and high transverse momenta on the same footing. We illustrate the formalism by calculating the differential cross section...
Parton energy loss has been established as an essential signature of the QGP in heavy ion collisions since the earliest measurements at RHIC indicating suppression of hadron spectra at high $p_{T}$ and coincidence yields. Understanding this phenomenon of jet quenching is a requirement for extracting the microscopic properties of the QGP via jet-tomography. STAR has recently introduced a...
One of the primary goals of flow studies in heavy-ion collisions during recent years is a better understanding of the transport properties of the quark-gluon plasma (QGP), such as the temperature dependence of the shear viscosity to entropy density ratio, $\eta/s(T)$. The higher order harmonic flow observables ($n > 3$) and their non-linear response to the initial state anisotropy has the...
Recent measurements and hydrodynamic model calculations suggest that the higher-order flow coefficients, $v_{n}$ (n $>$ 3), have two contributions: a linear contribution driven by the initial-state eccentricities, $\epsilon_{n}$, and a mode-coupled contribution derived from the lower-order eccentricity coefficients $\epsilon_{2}$ and $\epsilon_{3}$. Measurement of these two contributions to...
Jets engender physics over a multitude of scales, from the hardest interactions in a heavy-ion collision (up to a TeV at the LHC), down to the scale of the freeze-out temperature. A complete description of jet modification must address the role and interplay of the physics at each of these scales and their effect on a wide variety of integrated and differential jet observables.
In this...
Nowadays powerful accelerators collide heavy-ions at high energies in order to recreate the Quark Gluon Plasma (QGP) which is a hot and dense state of matter that is believed to have filled our universe shortly after the Big Bang. We propose a new approach to study the QGP by using very energetic jets produced in the same collisions which can be utilized as controllable hard probes. Measuring...
In holographic heavy ion collisions it is possible to follow both the energy density and a globally conserved (baryon) number density throughout the evolution, dual to a metric and Maxwell field in the dual bulk theory, respectively. At infinite coupling, past work has shown that after the collision the baryon number ends up around mid-rapidity, which is different from high energy heavy ion...
The observed suppression of inclusive jets in heavy-ion collisions at LHC has a very weak $p_{T}$ dependence over a large range of $p_{T}$ = 50-1000 GeV and is almost independent of the colliding energy, though the initial energy density of the formed QGP has increased significantly from $\sqrt{s}$ = 2.76 to 5.02 TeV. This interesting phenomenon is fully investigated in the linear Boltzmann...
We propose a new and improved principal component analysis (PCA), which characterizes the fluctuations of anisotropic flow and how these fluctuations are correlated in transverse momentum. Then, using state-of-the-art hydrodynamic simulations, we make an explicit connection between the initial geometry and these principal components. The usual eccentricity scaling of anisotropic flow implies...
To assess the properties of the quark-gluon plasma formed in heavy ion collisions, correlations between the mean transverse momentum, [$p_{T}$], and the magnitude of the flow harmonics, $v_{n}$, are measured by the ATLAS experiment at the LHC. The analysis uses data samples of lead-lead collisions at $\sqrt{s_{NN}} =5.02$~TeV and proton-lead collisions at $\sqrt{s_{NN}} =5.02$~TeV,...
J-PARC is one of the world’s highest-intensity proton accelerators for material and life sciences, neutrino physics, and hadron and nuclear physics. By acceleration of heavy-ion beams, J-PARC could also become a high-intensity frontier heavy-ion beam facility. For heavy-ion acceleration, we will build a new compact heavy-ion linac and a booster ring as an injector, while we utilize the...
The spatial anisotropy of QGP, formed in ultrarelativistic heavy-ion collisions, is commonly inferred form models of early QGP evolution. These studies (e.g. MC-Glauber, EKRT, IP-Glasma, MC-KLN), based on different methods, lead to notably different predictions, with a notable effect in the resulting predictions for both low and high pt data. On the other hand, energy loss of high-pt particles...
Medium-induced parton splitting is the building block for jet evolution in the presence of a hot QCD medium and plays a central role in quantitative studies of jet quenching. It exhibits two regimes: the one dominated by one single hard scattering at high frequency, and the other by multiple soft scattering at low frequency. A closed analytic formula encompassing both regimes is so far...
The large samples of high-quality data taken in pp collisions at $\sqrt{s} = 5$, 7 and 13 TeV and in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV at the LHC with the ALICE detector allows a systematic study of light (anti-)nuclei production to be performed in these collision systems. The excellent performance of the Inner Tracking System, Time-Projection Chamber and Time-Of-Flight...
A precise understanding of the Equation of State of dense objects like neutron stars is limited by the knowledge about the hyperon interaction and the precision of the models describing the latter. Traditionally, meson exchange models are used to describe the hyperon sector and are constrained by the scarce scattering and hypernuclei data, almost exclusively available for $\Lambda$ hyperons....
Studies of jet structure in heavy-ion collisions can provide information about the mechanism of jet quenching in the hot and dense QCD medium created in these collisions and about its properties over a range of distance scales. This talk presents the latest ATLAS measurement of the internal structure of jets to shed more light on the modification of the parton showering process in the presence...
In the presence of the large initial angular momentum occurring in non-central heavy-ion collisions, vector mesons can be polarized due to spin-orbital-angular-momentum interaction or they can be polarized during the hadronization process from polarized quarks. Experimentally, this phenomenon can be studied by measuring the angular distribution of the decay daughters of vector mesons with...
We calculate the mean-over-variance ratio of the net-kaon fluctuations in the Hadron Resonance Gas (HRG) model for the five highest energies of the RHIC Beam Energy Scan (BES) for different particle data lists. We compare these results with the most recent experimental data from the STAR collaboration in order to extract sets of chemical freeze-out parameters for each list. We focused on...
Measurements of jets produced in collisions of heavy ions, such as dijet asymmetry, boson-jet momentum imbalance, and inclusive jet spectra, have consistently indicated final states of less energy as compared to pp collisions. This energy loss is interpreted as a signature of the quark-gluon plasma. Subsequent studies have shown that the energy lost by jets is redistributed to large angle and...
Measurements of the polarization of the particles produced in relativistic heavy-ion collisions can provide insights into the initial conditions and evolution of the strongly interacting system during a collision. The global spin alignment is quantified by the diagonal spin density matrix element ($\rho_{00}$) with respect to the quantization axis, i.e. normal to the reaction plane. In...
We present measurements of the semi-inclusive distribution of charged jets recoiling from a trigger hadron in pp and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. This
technique provides precise, data-driven suppression of the large uncorrelated background in such measurements. It uniquely enables the exploration of medium-induced modification of jet production and acoplanarity...
The study of light flavour (u,d,s) hadron production plays an important role in understanding the dynamics of the strongly-interacting system created in nucleus-nucleus collisions, the
Quark-Gluon Plasma (QGP). Historically, it has been assumed that no QGP is formed in small collision systems, but this paradigm is challenged by the observation of collective-like behaviour and strangeness...
We revisit the azimuthal angle dependence of the local spin polarization of hyperons in heavy-ion collisions at 200 GeV in the framework of the (3+1)D viscous hydrodynamic model CLVisc. Two different initial conditions are considered in our simulation: the optical Glauber initial condition without initial orbital angular momentum and the AMPT initial condition with an initial orbital angular...
Strangeness (especially the multi-strangeness) production has been suggested as a sensitive probe to the early dynamics of the deconfined matter created in heavy ion collisions. The ratios of particle yields involving strange particles are often utilized to study various properties of nuclear matter, such as the strangeness chemical potential and the chemical freeze-out temperature. The yield...
Using the CUJET3 framework [1], we predict dijet acoplanarity observables using jet-medium couplings that are $\chi^2$ constrained by global RHIC&LHC $R_{AA}$ data, thereby significantly extending our previous work in [2]. We compare the predicted dijet relative azimuthal angle distributions for jets propagating through both perturbative (wQGP/HTL) and nonperturbative (sQGMP) models of the...
Mostly based on: F. Becattini, W. Florkowski, Phys. Lett. B 789 (2019) 419-425
The search for and the recent evidence of polarization in relativistic heavy
ion collisions has raised fundamental questions about the most general theoretical
description of a relativistic polarizable neutral medium and especially about
the role of the spin tensor in relativistic hydrodynamics. The...
The thermodynamic properties of high temperature and high density QCD-matter are explored within the Chiral SU(3)-flavor parity-doublet Polyakov-loop quark-hadron mean-field model, CMF. The applications of the CMF model to the lattice QCD data, heavy-ions physics, and static neutron stars are presented. In the CMF-model the transition between hadron-dominated and quark-dominated regimes is...
Collisions of small systems exhibit evidence of collective behavior through various flow type measurements, which suggests that quark gluon plasma could be produced in these collisions. If so, there could also be evidence for energy loss in the plasma, which would present itself in the spectra of hadrons. PHENIX has studied the nuclear modification factor $R_{AB}$ of various hadron species at...
Pythia8 is the only general purpose event generator able to produce
fully exclusive hadronic final states in collisions involving heavy
ions. This is done by carefully stacking individual parton-level
nucleon-nucleon collisions together according to the so-called
Angantyr model. The sub-events are produced using the full Pythia8
machinery with initial and final state parton showers and...
We propose a microscopic description for the polarization from the first principle through the spin-orbit coupling in particle collisions. The model is different from previous ones based on local equilibrium assumptions for the spin degree of freedom. It is based on scatterings of particles as wave packets, an effective method to deal with particle scatterings at specified impact parameters....
There have been various attempts to give lower limits on the location of the QCD critical endpoint via lattice simulations. These mostly rely on expanding the pressure in a Taylor series near zero chemical potential, and use estimators for the radius of convergence, mostly the ratio estimator. If the radius of convergence can be found, it gives a lower limit on the location of a true phase...
Lambda polarization $P_{\Lambda/\bar{\Lambda}}$ was measured by the STAR collaboration [1], confirming the existence of extremely large vorticities within the Quark-Gluon Plasma (QGP). A recent study using a high-statistics data set at $\sqrt{s_{NN}} = 200$ GeV has shown the dependence of $P_{\Lambda/\bar{\Lambda}}$ on collision centrality, azimuthal angle ($\varphi$), transverse momentum...
We present the first measurements of diffraction in $\sqrt{s_{NN}}=8.16$ TeV proton-lead collisions within CMS. The very large angular coverage of CMS is used to tag rapidity gaps on both the proton-going and lead-going sides and to identify both pomeron-lead and pomeron-proton topologies. Since the previous highest energy measurement of these processes was at $\sqrt{s_{NN}}=30$ GeV, the...
Heavy quarks (charm and beauty) are ideal probes to investigate the properties of the Quark-Gluon Plasma (QGP) produced in ultra-relativistic heavy-ion collisions, being produced in hard-parton scatterings in the collision early stages and experiencing the whole QGP evolution.
Measurements of heavy-flavour jets give a direct access to the initial parton kinematics and can provide constraints...
We present results for azimuthal anisotropies in p+p, p+Au, d+Au, and 3He+Au collisions at 200 GeV center of mass energy, using a hybrid IP-Glasma + MUSIC + UrQMD model, which is fully constrained by experimental data on Au+Au collisions. We compare to experimental data for $v_n(p_T)$, $c_2\{4\}$, and $C_{112}$ from the PHENIX and STAR Collaborations. We discuss the role of initial state...
We propose a new scenario characterizing the transition of the quark-gluon plasma (QGP) produced in heavy-ion collisions from a highly non-equilibrium state at early times toward a fluid described by hydrodynamics at late times. In this scenario, the bulk evolution is governed by a set of slow modes, after an emergent time scale τ_{Redu} when the number of modes that govern the bulk evolution...
We explore features of harmonic flow in ultra-relativistic collisions involving light nuclei. For the light-light nuclear collisions, such as 16O-16O reaction considered for the upcoming experimental program at RHIC and the LHC, we make definite predictions based on ratios of cumulants. We also point out very interesting aspects of the light-heavy collisions, where the light nucleus is...
We suggest a novel link between rotation and magnetic field in a charged fluid system: a magnetic field naturally arises along the fluid vorticity direction from the currents associated with the swirling charges. This general connection is demonstrated both for a single particle and for a fluid vortex. Applying the idea for heavy ion collisions we propose it as a new mechanism for generating...
Photons and Z boson can be used to constrain the kinematics, as well as the flavor, of the recoiling parton, before its interaction with the quark-gluon plasma. While photons are more abundant, they suffer from larger systematic uncertainties, particularly at low $p_\mathrm{T}$, from the background photons from neutral meson decays. Tagging with Z bosons is a complementary way to study...
Measurements of two-particle correlations in $pp$ collisions have demonstrated long-range azimuthal correlations between charged particle pairs, commonly interpreted as arising from a single particle azimuthal anisotropy. To better illuminate the origin and nature of these collective signatures, ATLAS presents studies in proton-proton collisions with a novel handle on event geometry, and in...
We study fermion mass correction to chiral kinetic equations in electromagnetic fields. Different from the chiral limit where fermion number density is the only independent distribution, the number and spin densities are coupled to each other for massive fermion systems. To the first order in ̄h, we derived the quantum correction to the classical on-shell condition and the Boltzmann-type...
Measurements of reconstructed jets produced in conjunction with a high-$p_\mathrm{T}$ electroweak boson (photon or Z) offer a discerning way to study the quark gluon plasma (QGP) created in ultrarelativistic nucleus-nucleus collisions. The high-$p_\mathrm{T}$ boson tags the initial energy, direction, and flavor of the opposing parton or partons before they begin to shower and propagate through...
We show how far-from-equilibrium hydrodynamics may be systematically defined, for arbitrary flow profiles, in terms of a generalized tensorial expansion with transport coefficients that contain an all order resummation in gradients. In this formulation, the transport coefficients of far-from-equilibrium fluid dynamics depend not only on the microscopic properties of the system but also on the...
We calculate the Wigner function for massive spin-1/2 particles in an inhomogeneous electromagnetic field to leading order in the Planck constant. Going beyond leading order in $\hbar$ we then derive a generalized Boltzmann equation in which the force exerted by an inhomogeneous electromagnetic field on the particle dipole moment arises naturally. Furthermore, a kinetic equation for this...
Measurements of long-range two- and multi-particle correlations have long provided critical insights into the properties of the strong coupled matter created in heavy-ion collisions. They have also provided hints that a shorty lived QGP may exist in smaller systems. We will present new results on long-range two-particle correlations for different charged particles multiplicities in pp at...
The high energies available at the CERN LHC have opened up the possibility to measure various large-mass elementary particles for the first time in heavy ion collisions. The first observation of top quark pair ($\mathrm{t\bar{t}}$) production is reported using lead-lead collisions recorded in 2018 by the CMS experiment at a nucleon-nucleon center-of-mass energy of...
The formulation of relativistic hydrodynamics of particles with spin 1/2 will be shortly reviewed. The proposed framework is based on the Wigner function treated in a semi-classical approximation or, alternatively, on a classical treatment of spin 1/2. The consistency of the two approaches will be demonstrated and first numerical solutions of the obtained scheme will be shown. Several...
The initial conditions for matter produced in the fragmentation region of high
energy hadronic collisions can be computed using the theory of the Color Glass Condensate. We consider the scattering of a classical color charge from a large nucleus and compute produced radiation in the fragmentation region of the classical color charge. Our results are to all order in the strength of the color...
We investigate whether the quark gluon plasma (QGP) is created in small colliding systems through the analysis of strangeness enhancement using the dynamical core--corona initialization model [1].
The yield ratios of (multi-)strange hadrons to charged pions in various colliding systems exhibit monotonic increase and scale with multiplicity at the LHC energies [2]. Motivated by these data,...
The next-to-leading order (NLO) Balitsky-Kovchegov (BK) equation describing the high-energy evolution of the scattering between a dilute projectile and a dense target suffers from instabilities unless it is supplemented by a proper resummation of the radiative corrections enhanced by large transverse logarithms. These instabilities are associated with large, anti-collinear, double logarithms...
Anisotropic flow is a useful observable to quantify the transport properties of the Quark Gluon Plasma (QGP) produced in heavy-ion collisions and to probe the hydrodynamic flow in small collision systems e.g. proton-proton (pp) and proton-lead (p--Pb) collisions. The experimental observed "correct" signs of multi-particle cumulants of $v_n$ coefficient in small collision systems, in...
We present the quantum kinetic equation for spin polarization of massive quarks in leading log order of perturbative QCD, which describes time evolution of the spin density matrix in momentum space of a massive quark interacting with a background QCD plasma. We find that the time evolution operator of the spin density matrix, or the quantum kinetic collision terms, are universally of order...
High energy particles traversing through medium primarily
lose energy by showering through hard bremsstrahlung and pair production. These splitting
processes are coherent over large distances in the very high energy limit, leading to suppression
from the Landau-Pomeranchuk-Migdal (LPM) effect. Avoiding soft-emission approximations,
we study the cases where the coherence lengths of two...
The measurement of low-energy cosmic anti-deuterons may reveal the existence of exotic processes such as dark-matter annihilation, since the production rate of these ions through ordinary secondary processes is very low. However, the lack of experimental data at low energies, where both the anti-deuteron production and inelastic cross sections are very poorly known, prevents precise...
Dielectrons are suggested as excellent probes of the hot and dense medium created in relativistic heavy-ion collisions due to their minimal interactions with the partonic and hadronic medium. They can carry the information from the initial to the final stage of a collision. The study of the dielectron mass spectrum could help to disentangle various contributions. In the low mass region (LMR,...
Elucidation of the quark matter properties at finite densities is one of the goals for the Beam Energy Scan (BES) programs at RHIC. For quantitative predictions and analyses of the experimental data, an equation of state at finite chemical potentials is needed as input to hydrodynamic models.
We construct the QCD equation of state at finite chemical potentials including net baryon (B),...
Beauty quarks are considered to be one of the best probes of the strongly interacting medium created in relativistic heavy-ion collisions as they are predominantly produced via initial hard scatterings. Measurements of B mesons provide information on the diffusion of beauty quarks as well as the flavor dependence of in-medium energy loss. In these studies, clarifying the hadronization...
The production of low-mass dielectrons is the most promising tool for the understanding of the chiral symmetry restoration and of the properties of the Quark-Gluon Plasma (QGP)
created in heavy-ion collisions. At low invariant mass, the dielectron production is sensitive to the properties of vector mesons in the medium related to the chiral symmetry
restoration. In the intermediate-mass...
Provided by the large beauty quark mass, beauty production is sensitive to test pQCD calculation as well as the nuclear matter effects in heavy ion collisions. In this talk, the measurement of open beauty hadron and Upsilon production in pPb data at nucleon-nucleon center-of-mass energy 8.16 TeV is presented. Nuclear matter effects, including the modification of gluon PDF and beauty...
Masses and radii of neutron stars and the recent data from LIGO suggest that
the sound velocity is greater than or of the order of 1/3 at densities a few times that of nuclear matter. We show that this arises naturally if nuclear matter is Quarkyonic. Quarkyonic matter has a shell in the Fermi surface of nuclear matter
and Fermi sea of quarks. We discuss how this shell might arise dynamically
Recent lattice QCD calculations show strong indications that the chiral crossover of QCD at zero baryon chemical potential (µ) is a remnant of the second order chiral phase transition. Furthermore, the non-universal parameters needed to map temperature T and µ to the universal properties of the second order chiral phase transition also have been determined by lattice QCD calculations....
Using novel lattice (non-relativistic) QCD techniques, for the first time, we will present results pertaining to the fate of $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(3S)$ in QGP. We will present results on how the masses of these states change with temperature, as well as how their spatial sizes change. Finally, we will also show new lattice QCD results on excited P-wave bottomonia in QGP.
In heavy-ion reactions at beam energies of a few GeV per nucleon on stationary targets, QCD matter is substantially compressed (2-3 times nuclear saturation density) while temperatures are expected not to exceed T = 70 MeV. Matter under such conditions is being studied with HADES at SIS18.
This contribution discusses new experimental results on the mechanisms of strangeness production, the...
Quark-hadron continuity has been well understood for three-flavor symmetric nuclear and quark matter, which is however a theoretically over-idealized environment. In this talk we clarify how quark-hadron continuity can be applied to neutron matter in the realistic neutron star environment. Our key observation is that neutron matter can be smoothly connected to the two-flavor...
A remarkable achievement of the relativistic heavy-ion program is the realization that relativistic fluid dynamics can describe the evolving system of quark-gluon plasma (QGP) from its early moments to a time when the growing mean-free-paths drive the system out of equilibrium. The effectiveness of this hydrodynamic description is judged by comparing calculated hadronic observables with...
The last decade of hadron spectroscopy has unveiled a wealth of states that do not have the properties expected of particles composed of 2 or 3 valence quarks. Among the most intriguing of these exotics is the X(3872), which various models attempt to describe as a hadronic molecule, a compact tetraquark, an unexpected charmonium state, or their mixtures. To date, most experimental studies of...
Merging binaries of neutron stars are not only strong sources of gravitational waves, but also have the potential of revealing states of matter at densities and temperatures not accessible in laboratories. A crucial and longstanding question in this context is whether quarks are deconfined as a result of the dramatic increase in density and temperature following the merger. We present the...
Using recent results on higher order cumulants of conserved charge fluctuations from lattice QCD, we construct mean, variance, skewness and kurtosis of net-strangeness, net-baryon number and net-electric charge distributions at next-to-leading order in $\mu_B$. For the strangeness neutral case ($\mu_S=0$) at fixed ratio of electric charge to baryon number density ($\frac{n_Q}{n_B}=0.4$), which...
Sharing and transfer of chirality between gauge fields and fermion plays a crucial role for understanding the dynamics of anomalous transport phenomena such as the Chiral Megnetic Effect. We present a first principles study of the chirality transfer between gauge fields and fermions based on classical-statistical real-time lattice simulations. We demonstrate that a chirality imbalance in the...
The exotic meson $\chi_{c1}(3872)$, also known as $X(3872)$, was discovered a decade ago, but the structure of this new state is still under debate. The masses of possible charmonium states from calculations using constituent quark models are too large, and therefore an explanation of the underlying characteristics of this meson remains a challenge. The similarity of the $\chi_{c1}(3872)$ mass...
Evidence for thermalization of the QCD matter created in high-energy nuclear collisions has dominantly come from the agreement of the measured yield of produced hadrons with those from statistical thermal models. Ideally for a thermalized system, in addition to mean, the higher orders of the moments of the multiplicity distribution of produced particles should also show agreement with thermal...
PHENIX measurements of low $p_T$ direct photons in Au+Au collisions at 200 GeV show large yields and simultaneously large anisotropies with respect to the reaction plane. Calculations of thermal photon emission fall short in describing the yield and the anisotropy at the same time. Furthermore, a recent publication of the STAR collaboration indicates lower direct photon yields in Au+Au...
(1) Zimanyi Medal in Nuclear Theory
(2) Elsevier Young Scientist Award
The region of the QCD phase diagram at high $\mu_{\rm B}$ can be accessed by fixed-target experiments working at future or existing facilities providing nuclear beams in the multi-GeV energy range. In particular, the CERN SPS is able to provide high-intensity beams over a wide energy interval ($\sqrt{s_{\rm NN}}=$ 5-17 GeV) that are ideal for the study of rare signals. Recently, an expression...
