We present the analyses of single electrons from semileptonic bottom and charm hadron decays at mid-rapidity in $\sqrt{s_{NN}}$ = 200 and 54.4 GeV Au+Au collisions (talk in Heavy-Flavor session III). The data at $\sqrt{s_{NN}}$ = 200 GeV incorporate information from the Heavy Flavor Tracker which enables the topological separation of electrons originating from bottom and charm hadron decays. We report the first STAR measurements at $\sqrt{s_{NN}}$ = 200 GeV of $v_{2}$ for bottom decay electrons as a function of $p_{T}$ and $v_{1}$ for charm decay electrons as a function of electron rapidity. Additionally, we present the improved measurements of heavy-flavor decay electron $R_{AA}$ and a new measurement of the ratio of $R_{CP}$ between bottom and charm decay electrons. Finally, we also report the measurement of non-photonic electron $v_{2}$ in $\sqrt{s_{NN}}$ = 54.4 GeV data collected during the 2017 RHIC run.
In this proceeding, we present the new precise directed flow $v_{1}$, measurement of $π$, $K$, $p$ and $ϕ$ in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 27, 54.4 GeV and deuteron at $\sqrt{s_{\rm NN}}$ = 7.7, 11.5, 14.5 and 19.6 GeV. The first measurement of pseudorapidity and centrality dependence of the $v_{1}$ of high-$p_{T}$ ($>$5 GeV/$c$) charged hadrons in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV are reported. The elliptic flow $v_{2}$, of identified hadrons ($π$, $K$, $p$, $ϕ$, $K^{0}_{S}$, $Λ$, $Ξ$, $Ω$) in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 54.4 GeV are also presented. …
Measurements of anisotropic flow in heavy-ion collisions provide insight into the early stage of the system's evolution. This proceedings presents directed and elliptic flow for Au+Au collisions at 39, 11.5 and 7.7 GeV, and for Cu+Cu at 22.4 GeV, measured in the STAR Experiment at RHIC. Differential measurements of directed and elliptic flow of charged particles as a function of centrality, transverse momentum and pseudorapidity are discussed.
The directed and elliptic flow of protons and charged pions has been observed from the semi-central collisions of a 158 GeV/nucleon Pb beam with a Pb target. The rapidity and transverse momentum dependence of the flow has been measured. The directed flow of the pions is opposite to that of the protons but both exhibit negative flow at low pt. The elliptic flow of both is fairly independent of rapidity but rises with pt.
New data with a minimum bias trigger for 158 GeV/nucleon Pb + Pb have been analyzed. Directed and elliptic flow as a function of rapidity of the particles and centrality of the collision are presented. The centrality dependence of the ratio of elliptic flow to the initial space elliptic anisotropy is compared to models.
Directed and elliptic flow of protons and positively charged pions has been studied in the target fragmentation region using the Plastic Ball detector in the WA98 experiment. The results exhibit a strong dependence on centrality, rapidity, and transverse momentum. The rapidity dependence can be described by a Gaussian distribution. The model comparisons reveal a large discrepancy of the flow strength obtained from the data and the simulations.
Directed and elliptic flow measurements for charged pions and protons are reported as a function of transverse momentum, rapidity, and centrality for 40 and 158A GeV Pb + Pb collisions as recorded by the NA49 detector. Both the standard method of correlating particles with an event plane, and the cumulant method of studying multiparticle correlations are used. In the standard method the directed flow is corrected for conservation of momentum. In the cumulant method elliptic flow is reconstructed from genuine 4, 6, and 8-particle correlations, showing the first unequivocal evidence for collecti…
PHOBOS measurements of elliptic flow are presented as a function of pseudorapidity, centrality, transverse momentum, energy and nuclear species. The elliptic flow in Cu-Cu is surprisingly large, particularly for the most central events. After scaling out the geometry through the use of an alternative form of eccentricity, called the participant eccentricity, which accounts for nucleon position fluctuations in the colliding nuclei, the relative magnitude of the elliptic flow in the Cu-Cu system is qualitatively similar to that measured in the Au-Au system.
Directed and elliptic flow are reported for charged pions and protons as a function of transverse momentum, rapidity, and centrality in 40 and 158 AGeV Pb + Pb collisions. The standard method of correlating particles with an event plane is used. The directed flow of protons is small and shows little variation near to midrapidity, but rises fast towards projectile rapidity in the 40 AGeV data. For most peripheral collisions the flat region becomes negative resulting in $v_1$ changing sign three times. Elliptic flow doesn't seem to change very much from 40 AGeV to 158 AGeV. The difference is sma…
The directed flow of particles produced in ultrarelativistic heavy ion collisions at SPS and RHIC is so small that currently available methods of analysis are at the border of applicability. Standard two-particle and flow-vector methods are biased by large nonflow correlations. On the other hand, cumulants of four-particle correlations, which are free from this bias, are plagued by large statistical errors. Here, we present a new method based on three-particle correlations, which uses the property that elliptic flow is large at these energies. This method may also be useful at intermediate ene…
We compare microscopic transport model calculations to recent data on the directed and elliptic flow of various hadrons in 2 - 10 A GeV Au+Au and Pb (158 A GeV) Pb collisions. For the Au+Au excitation function a transition from the squeeze-out to an in-plane enhanced emission is consistently described with mean field potentials corresponding to one incompressibility. For the Pb (158 A GeV) Pb system the elliptic flow prefers in-plane emission both for protons and pions, the directed flow of protons is opposite to that of the pions, which exhibit anti-flow. Strong directed transverse flow is pr…
The directed and elliptic flow in collisions of $^{112}Sn$ + $^{112}Sn$ at energies from 35 to 90 MeV/nucleon were studied in an isospin-dependent quantum molecule dynamics model (IQMD). With increasing incident energy, the directed flow rises from the negative flow to the positive flow. Its magnitude depends on the nuclear equation of state (EOS). However, the elliptic flow shows decrease with increasing incident energy and its magnitude is not very sensible to EOS. Systematic studies of the impact parameter dependence and cluster mass dependence were also performed. The study of directed flo…
Directed and elliptic flow for the Au + Au system at incident energies between 40 and 150 MeV per nucleon has been measured using the INDRA 4 pi multi-detector. For semi-central collisions, the elliptic flow of Z <= 2 particles switches from in-plane to out-of-plane enhancement at around 100 MeV per nucleon, in good agreement with the result reported by the FOPI Collaboration. The directed flow changes sign at a bombarding energy between 50 and 60 MeV per nucleon and remains negative at lower energies. The conditions for the appearance and possible origins of negative flow are discussed.
We present the directed flow measurement ($v_1$) from Au+Au collisions at $\sqrtsNN = 62$ GeV. Over the pseudorapidity range we have studied, which covers $η$ from -1.2 to 1.2 and $2.4 < |η| < 4$, the magnitude of $v_1$ for charged particles is found to increase monotonously with pseudorapidity for all centralities. No ``$v_1$ wiggle'', as predicted by various theoretical models, is observed at midrapidity. Elliptic flow ($v_2$) from moderate high $p_t$ particles ($3-6 GeV/c$) at $\sqrtsNN = 200$ GeV is presented as a function of impact parameter. It is found that models that are based on {\it…
We investigate the elliptic and the triangular flow of heavy mesons in ultrarelativistic heavy-ion collisions at RHIC and the LHC. The dynamics of heavy quarks is coupled to the locally thermalized and fluid dynamically evolving quark-gluon plasma. The elliptic flow of $D$ mesons and the centrality dependence measured at the LHC is well reproduced for purely collisional and bremsstrahlung interactions. Due to the event-by-event fluctuating initial conditions from the EPOS2 model, the $D$ meson triangular flow is predicted to be nonzero at $\sqrt{s}=200$ GeV and $\sqrt{s}=2.76$ TeV. We study th…
We present a detailed analysis of the beam energy dependence of the mechanisms for the generation of directed and elliptic flows in Au+Au collisions focusing on the role of hadronic rescattering and spectator shadowing within a microscopic transport model JAM with different equation of state. A systematic study of the beam energy dependence is performed for Au+Au collisions at $\sqrt{s_{NN}} =2.3 - 62.4$ GeV. The transition of the dynamical origin of the directed flow is observed. We find that the initial Glauber type nucleon-nucleon collisions generate negative $v_1$ for nucleons at midrapidi…
The splitting of elliptic flow measured in different regions of the momentum space of produced hadrons has been recently studied in transport models and proposed as a sensitive probe of the angular momentum carried by the fireball produced in a relativistic heavy ion collision. The initial state angular momentum also gives rise to rapidity odd directed flow which has been measured. We consider a relativistic hydrodynamic framework with the initial matter distribution suitably calibrated to describe the observed directed flow and apply it to study the spilt in the elliptic flow. Our study sugge…
In this paper we propose to thoroughly investigate asymmetric nuclear collisions both in the fixed target mode at the laboratory energy below 5 GeV per nucleon and in the collider mode with a center of mass energy below 11 GeV per nucleon. Using the UrQMD transport model, we demonstrate a strong enhancement of directed and elliptic flow coefficients for the midcentral asymmetric nuclear collisions compared to symmetric collisions. We argue that such an enhancement is due to the disappearance of the nuclear shadowing effect on the side of the smaller projectile nucleus. An analysis of the energ…
The propagation of charm and bottom quarks through an ellipsoidal domain of quark gluon plasma has been studied within the ambit of non-equilibrium statistical mechanics. Energy dissipation of heavy quarks by both radiative and collisional processes are taken in to account. The experimental data on the elliptic flow of the non-photonic electrons resulting from the semi-leptonic decays of hadrons containing heavy flavours has been reproduced with the same formalism that has been used earlier to reproduce the nuclear suppression factors. The elliptic flow of the non-photonic electron from heavy …
Thermalized matter created in non-central relativistic heavy-ion collisions is expected to be tilted in the reaction plane with respect to the beam axis. The most notable consequence of this forward-backward symmetry breaking is the observation of rapidity-odd directed flow for charged particles. On the other hand, the production points for heavy quarks are forward-backward symmetric and shifted in the transverse plane with respect to the fireball. The drag of heavy quarks from the asymmetrically distributed thermalized matter generates a large directed flow for heavy flavor mesons. We predict…
We extend our POWLANG transport setup for the modelling of heavy-flavour production in heavy-ion collisions to the case of full 3+1 simulations, dropping the approximation of longitudinal boost-invariance of the background medium. This enables us to provide predictions for observables for which the rapidity dependence is essential in order to obtain a non-vanishing signal, like the directed flow $v_1$, and to get reliable results also for kinematic distributions of heavy-flavour particles at forward rapidity. We compare our predictions with experimental data obtained in Au-Au and Pb-Pb collisi…
We report on the first evidence for a non-zero rapidity-odd directed flow ($v_{1}$) for $D^{0}$ and $\overline{D^{0}}$ mesons in 10-80\% centrality Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200~GeV measured with the STAR detector at RHIC. The slope of the $v_1$ rapidity dependence ($dv_{1}/dy$) averaged over $D^{0}$ and $\overline{D^{0}}$ mesons is -0.081 $\pm$ 0.021 $\pm$ 0.017, while that of charged kaons is -0.0030 $\pm$ 0.0001 $\pm$ 0.0002, suggesting significantly larger slope for the $D^{0}$ mesons. Models indicate that the large $dv_{1}/dy$ of $D^{0}$ mesons is sensitive to the initiall…
Recently the splitting of elliptic flow $v_2$ at finite rapidities has been proposed as a result of the global vorticity in non-central relativistic heavy ion collisions. In this study, we find that this left-right (i.e., on opposite sides of the impact parameter axis) splitting of the elliptic flow at finite rapidities is a result of the non-zero directed flow $v_1$, with the splitting magnitude $\approx 8v_1(1-3v_2)/(3π)$. We also use a multi-phase transport model, which automatically includes the vorticity field and flow fluctuations, to confirm the $v_2$ splitting. In addition, we find tha…
Directed and elliptic flow of light nuclei and hypernuclei in Au+Au collisions at $\sqrt{s_\mathrm{NN}}=3$ GeV: Coalescence vs. Statistical Fragmentation
Directed and elliptic flow of inclusive photons near mid-rapidity in $158 $A GeV Pb+Pb collisions has been studied. The data have been obtained with the photon spectrometer LEDA of the WA98 experiment at the CERN SPS. The flow strength has been measured for various centralities as a function of $p_T$ and rapidity over $0.18 < p_T < 1.5 \mathrm{GeV}/c$ and $2.3 < y < 2.9$. The angular anisotropy has been studied relative to an event plane obtained in the target fragmentation region that shows the elliptic flow to be in-plane. The elliptic flow has also been studied using two-particle correlatio…
Within a transport model coupled with a microscopic coalescence model, the directed and elliptic flows of protons and deuterons as well as their scalling properties are studied in the centrality of 20-30% Au+Au collisions at $\sqrt{s_{\rm NN}}=2.4$ GeV. It is found that the flows as well as their scaling properties simulated with the isospin- and momentum-dependent nuclear mean field with an incompressibility $K_{0}=230$ MeV fit fairly the HADES data, while those simulated with the commonly used momentum-independent nuclear mean field with an incompressibility $K_{0}=380$ MeV can only fit part…
Charm quarks, owing to their large mass, are produced predominantly in the initial hard scatterings in heavy-ion collisions, and therefore can be a valuable tool for studying the early time dynamics of these collisions. The rapidity-odd directed flow at mid-rapidity in heavy-ion collisions originates from a tilt in the reaction plane of the thermalized medium caused by the asymmetry between the number of participants from projectile and target nuclei as a function of rapidity. Recently, it has been predicted that the slope of the directed flow at mid-rapidity for $D^0$ mesons, arising from the…
We report recent results of strangeness and heavy flavor measurements from PHENIX. The topics are: Elliptic flow of strangeness and heavy flavor electron production comparing to the other hadrons, $ϕ$ meson production, and an exotic particle search.
Due to the large masses, heavy-flavor quarks are dominantly produced in initial hard scattering processes and experience the whole evolution of the medium produced in heavy-ion collisions at RHIC energies. They are also expected to thermalize slower than light-flavor quarks. Thus the measurement of heavy quark production and azimuthal anisotropy can provide important insights into the medium properties through their interactions with the medium. In these proceedings, we report measurements of $D^0$ production and elliptic flow ($v_2$) via topological reconstruction using STAR's recently instal…
The HFT, a new inner tracking detector for STAR, aims to measure the charmed hadron nuclear modification factor as well as their elliptic flow to the low $p_\mathrm{T}$ region ($\sim$0.5 GeV/c) by measuring the displaced vertices of charmed particles.
The paper presents recent PHENIX results for the nuclear modification factor R_AA in Au + Au Collisions at sqrt(s_NN) = 200 GeV for the electrons originating from semi-leptonic decays of open heavy flavor carrying particles. We also report the results of the azimuthal asymmetry (v_2) measurement for those electrons, which is directly related to the heavy quark elliptic flow.
Relativistic quantum molecular dynamics based on the relativistic mean field theory (RQMD.RMF) is extended by including momentum-dependent potential. The equation of state (EoS) dependence of the directed and the elliptic flow of protons in the beam energy range of $2.3 < \sqrt{s_{NN}}< 20$ GeV is examined. It is found that the directed flow depends strongly on the optical potential at high energies,$\sqrt{s_{NN}} > 3 $ GeV, where no information is available experimentally. The correlation between effective mass at saturation density and the optical potential is found: smaller values of effect…
In this contribution, the production of heavy-flavor hadrons as a function of multiplicity, via the study of the D-meson and heavy-flavor hadron decay leptons self-normalized yields in pp collisions at the center of mass energy $\sqrt{s} = 13$ TeV is discussed. Comparisons are made with similar measurements of J/$ψ$ at $\sqrt{s} = 13$ TeV and various model calculations. The $\mathrm{Λ_{c}^{+}/D^{0}}$ and $\mathrm{D^{+}_{s}/D^{0}}$ yield ratios in different multiplicity intervals in pp collisions at $\sqrt{s} = 13$ TeV are also reported. In addition, the ALICE measurement of $\mathrm{Λ_{c}^{+}}…
We propose to construct a heavy flavor tracker for the STAR experiment at RHIC in order to measure the elliptic flow of charmed hadrons in the low pt region and identify B-meson contributions in the region pt > 4 GeV/c. In this talk, we will present the design of the detector in-depth and its expected performance as studied in detailed simulations and analytic calculations. Physics potentials of the detector will also be discussed.
We report on measurements of directed flow as a function of pseudorapidity in Au+Au collisions at energies of $\sqrt{s_{_{NN}}} =$ 19.6, 62.4, 130 and 200 GeV as measured by the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). These results are particularly valuable because of the extensive, continuous pseudorapidity coverage of the PHOBOS detector. There is no significant indication of structure near midrapidity and the data surprisingly exhibit extended longitudinal scaling similar to that seen for elliptic flow and charged particle pseudorapidity density.
One unexpected recent result from heavy-ion collisions is the large suppression and elliptic flow of electrons from heavy flavor decay. Further measurements of properties of electrons from heavy flavor decay are crucial to understanding the origin of this suppression and its implications for the properties of the hot matter produced at RHIC. Two particle correlations have been used extensively to study the propagation of hard partons through the produced matter in heavy-ion collisions. Measurements in p+p collisions are important both as reference for heavy ion measurements and to study heavy …
We explore the system size dependence of heavy-quark-QGP interaction by studying the heavy flavor meson suppression and elliptic flow in Pb-Pb, Xe-Xe, Ar-Ar and O-O collisions at the LHC. The space-time evolution of the QGP is simulated using a (3+1)-dimensional viscous hydrodynamic model, while the heavy-quark-QGP interaction is described by an improved Langevin approach that includes both collisional and radiative energy loss inside a thermal medium. Within this framework, we provides a reasonable description of the $D$ meson suppression and flow coefficients in Pb-Pb collisions, as well as …
Measurements of quarkonia (heavy quark and antiquark bound states) and open-heavy flavour hadrons in hadronic collisions provide a unique testing ground for understanding quantum chromodynamics (QCD). Although recently there was significant progress, our understanding of hadronic collisions has been challenged by the observation of intriguing effects in high-multiplicity proton-proton (pp) and p-Pb collisions, such as collective phenomena. The excellent particle identification, track and decay-vertex reconstruction capabilities of the ALICE experiment are exploited to measure quarkonia as well…
We present recent results from Al(beam)+Au(target) collisions at $\sqrt{s_{NN}}=4.9$ GeV and Au+Au collisions at $\sqrt{s_{NN}}=4.5$\kern 0.16667em GeV from the STAR fixed-target (FXT) program. We report transverse mass spectra of protons, $K^0_S$ and $Λ$, rapidity density distributions of $π^\pm$, $K^0_S$ and $Λ$, directed flow of protons, $π^\pm$, $K^0_S$ and $Λ$, and elliptic flow of protons and $π^{\pm}$. These are the first measurements of pion directed and elliptic flow in this energy range at RHIC. Pion and proton elliptic flow show mass ordering. Measurements are compared with the publ…
Within an advanced Langevin-hydrodynamics framework coupled to a hybrid fragmentation-coalescence hadronization model, we study heavy flavor quenching and flow in relativistic heavy-ion collisions. We investigate how the initial heavy quark spectrum, the energy loss and hadronization mechanisms of heavy quarks in medium, the evolution profile of pre-equilibrium stage, the flow of medium and the temperature dependence of heavy quark diffusion coefficient influence the suppression and elliptic flow of heavy mesons at RHIC and the LHC. Our result shows that different modeling of initial condition…
The beam energy dependence of the elliptic flow,$v_2$, is studied in mid-central Au+Au collisions in the energy range of $3\leq \sqrt{s_{NN}} \leq 30$ GeV within the microscopic transport model JAM. The results of three different modes of JAM are compared; cascade-,hadronic mean field-, and a new mode with modified equations of state, with a first order phase transition (1.O.P.T.) and with a crossover transition. The standard hadronic mean field suppresses $v_2$, while the inclusion of the effects of a 1.O.P.T. (and also of a crossover transition) does enhance $v_2$ at $\sqrt{s_{NN}}<30$ GeV. …
We study the development of heavy-flavor flow harmonics in high-energy nuclear collisions. The elliptic and triangular flow of heavy-flavor hadrons, arising from the finite impact parameter of the two nuclei and from event-by-event fluctuations of the initial geometry, is analyzed in detail, considering the contribution from particles decoupling from the fireball at various times. We also study the dependence of the flow harmonics on the event-shape fluctuations, considering events belonging to the same centrality class but characterized by very different eccentricities (or vice-versa).
The elliptic azimuthal anisotropy coefficient ($v_2$) is measured for charm (D$^0$) and strange (K$_\mathrm{S}^0$, $Λ$, $Ξ^-$, and $Ω^-$) hadrons, using a data sample of pPb collisions collected by the CMS experiment, at a nucleon-nucleon center-of-mass energy $\sqrt{s_{_\mathrm{NN}}} =$ 8.16 TeV. A significant positive $v_2$ signal from long-range azimuthal correlations is observed for all particle species in high-multiplicity pPb collisions. The measurement represents the first observation of possible long-range collectivity for open heavy flavor hadrons in small systems. The results suggest…
We present a selection of recent heavy flavor results from the STAR experiment. Measurements of $D^0$ and $D^*$ meson production in $\sqrt{s}$=200 and 500 GeV p+p, as well as in $\sqrt{s_{NN}}$=200 GeV d+Au, Au+Au and 193 \GeV U+U collisions are presented and implications on the production mechanism are discussed. We report on the production and elliptic flow of electrons from semi-leptonic decays of heavy flavor hadrons in \snn{}=39, 62.4 and 200 GeV Au+Au collisions. Nuclear modification of $J/ψ$ production in $\sqrt{s_{NN}}$=39, 62.4 and 200 GeV Au+Au, and 193 GeV U+U, and of $Υ$ in 200 GeV…
The elliptic flow of muons from the decay of charm and bottom hadrons is measured in $pp$ collisions at $\sqrt{s}=13$ TeV using a data sample with an integrated luminosity of 150 pb$^{-1}$ recorded by the ATLAS detector at the LHC. The muons from heavy-flavor decay are separated from light-hadron decay muons using momentum imbalance between the tracking and muon spectrometers. The heavy-flavor decay muons are further separated into those from charm decay and those from bottom decay using the distance-of-closest-approach to the collision vertex. The measurement is performed for muons in the tra…
Directed and elliptic event anisotropy parameters measured in the experiments at relativistic heavy-ion collider are presented. The possible origin of the measured elliptic anisotropy parameter $v_2$ and its sensitivity to the early phase of the high-energy heavy-ion collisions are discussed.
The various flow phenomena observed at energies between 50 AMeV and 160 AGeV are reviewed. I first define three types of flow: directed flow and elliptic flow, which are the two first Fourier components of the azimuthal distribution in non-central collisions; radial flow, which is deduced from an analysis of transverse momentum spectra in central collisions. Then, I review the observations of directed flow and elliptic flow, with emphasis on recent results. I discuss their dependence on various parameters: global geometry (impact parameter, mass numbers of colliding nuclei and bombarding energ…
The large statistics accumulated during the LHC Run-1 and Run-2 have provided the unique opportunity to study the properties of the Quark-Gluon Plasma using rare hard probes. The ALICE Collaboration has presented new results on the jet shape observables in p--Pb and Pb--Pb collision. Using data from Run-2, the elliptic flow of open and hidden charm mesons have been measured with much better precision, confirming that charm quarks participate in the collective dynamic expansion with the medium. In p--Pb collisions the absence of jet quenching correlated with high event activity has been confirm…
To incorporate the effect of gluons on the evolution dynamics of the quark matter produced in relativistic heavy-ion collisions, we extend the 3-flavor Nambu-Jona-Lasinio (NJL) transport model to include the contribution from the Polyakov loops. Imbedding the resulting pNJL partonic transport model in an extended multiphase transport (extended AMPT) model, we then study the elliptic flow splittings between particles and their antiparticles in relativistic heavy-ion collisions at RHIC-BES energies. We find that a weak quark vector interaction in the partonic phase is able to describe the ellipt…
The determination of the color force in a quark-gluon plasma (QGP) is a key objective in the investigation of strong-interaction matter. Open and hidden heavy-flavor observables in heavy-ion collisions (HICs) are believed to provide insights into this problem by comparing calculations of heavy-quark (HQ) and quarkonium transport with pertinent experimental data. In this work, we utilize the $T$-matrix formalism to compute charm-quark transport coefficients for various input potentials previously extracted from simultaneous fits to lattice-QCD data for HQ free energies, quarkonium correlators a…
Using a partonic transport model based on the 3-flavor Nambu-Jona-Lasinio model and a relativistic hadronic transport model to describe, respectively, the evolution of the initial partonic and the final hadronic phase of heavy-ion collisions at energies carried out in the Beam-Energy Scan program of the Relativistic Heavy Ion Collider, we have studied the effects of both the partonic and hadronic mean-field potentials on the elliptic flow of particles relative to that of their antiparticles. We find that to reproduce the measured relative elliptic flow differences between nucleons and antinucl…
A Multi-Phase Transport (AMPT) model has been shown to describe experimental data well, such as the bulk properties of particle spectra and elliptic anisotropy ($v_{2}$) in heavy ion collisions. Recent studies have shown that AMPT describes the $v_{2}$ data in small system collisions as well. In these proceedings, we first investigate the origin of the mass ordering of identified hadrons $v_{2}$ in heavy ion as well as small system collisions. We then study the production mechanism of the charm $v_{2}$ in light of the escape mechanism for the light quark $v_{2}$.
Event-by-event hydrodynamics is applied to Cu-Au collisions at 200GeV. Predictions for charged particle distributions in pseudorapidity, transverse momentum spectra, femtoscopy radii are given. The triangular and elliptic flow coefficients are calculated. The directed flow at central rapidity in the reaction plane in asymmetric collisions is nonzero, fluctuations of the initial profile lead to a further increase of the directed flow when measured in the event plane.
We review the experimental and theoretical status of open heavy-flavor (HF) production in high-energy nuclear collisions at RHIC and LHC. We first overview the theoretical concepts and pertinent calculations of HF transport in QCD matter, including perturbative and non-perturbative approaches in the quark-gluon plasma, effective models in hadronic matter, as well as implementations of heavy-quark (HQ) hadronization. This is followed by a brief discussion of bulk evolution models for heavy-ion collisions and initial conditions for the HQ distributions which are needed to calculate HF spectra in…
We calculate open heavy-flavor (HF) transport in relativistic heavy-ion collisions by applying a strong-coupling treatment in both macro- and microscopic dynamics (hydrodynamics and non-perturbative diffusion interactions). The hydrodynamic medium evolution is quantitatively constrained by bulk and multi-strange hadron spectra and elliptic flow. The heavy quark (HQ) transport coefficient is evaluated from a non-perturbative $T$-matrix approach in the Quark-Gluon Plasma (QGP) which, close to the critical temperature, leads to resonance formation and feeds into the recombination of heavy quarks …
The directed and elliptic flow of protons and negative pions in 4.2A GeV/c C+C collisions is studied using the Fourier analysis of azimuthal distributions. It is found that the protons exhibit pronounced directed flow, while the flow of pions is either non existent or too weak to be detected experimentally. Also, it is found that in the entire rapidity interval the elliptic flow is very small if not zero. These results are confirmed by the Quark-Gluon-String Model (QGSM) and the relativistic transport model (ART 1.0), except that these models predict very weak antiflow of pions. The more detai…
Based on the newly updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model, the pion potentials obtained from the in-medium dispersion relation of the $Δ$-hole model and from the modified phenomenological approach are further introduced. Both the rapidity $y_0$ and transverse-velocity $u_{t0}$ dependence of directed $v_1$ and elliptic $v_2$ flows of $π^{+}$ and $π^{-}$ charged mesons produced from Au+Au collisions at two beam energies of 1.0 GeV/nucleon and 1.5 GeV/nucleon and within a large centrality region of $0<b_0<0.55$ are scanned. Calculations with pion potenti…
Relativistic quantum molecular dynamics with scalar and vector interactions based on the relativistic mean meson field theory, RQMD.RMF, is developed.It is implemented into the microscopic transport code JAM.The sensitivity of the directed and of the elliptic proton flow in high energy heavy-ion collisions on the stiffness of the RMF equation of state (EoS) is examined. These new calculations are compared to experimental data at mid-central Au + Au collisions in the beam energy range $2.5 < \sqrt{s_{NN}} < 20$ GeV. This new RQMD model with the relativistic mean field scalar and vector meson in…
