Yifei Zhang
We present an overview of the recent abundant measurements for charm production at RHIC. The significant information of charm cross sections in different collision system at 200 GeV and charmed hadron freeze-out and flow properties extracted from these measurements are presented. The heavy flavor energy loss in the medium and heavy flavor related azimuthal correlations in heavy ion collisions are also discussed.
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Recent experimental measurements on open charm production in proton-proton, proton (deuteron)-nucleus and nucleus-nucleus collisions at RHIC are reviewed. A comparison with theoretical predictions is made. Some unsettled issues in open charm production call for precise measurements on directly reconstructed open charm hadrons.
The latest results for open charm and $J/ψ$ production in p-p, d-Au and Au-Au from the PHENIX and STAR experiments at $\sqrt{s_{NN}}=200$ GeV at RHIC are presented. The preliminary data show open charm production follows binary scaling in d-Au and Au-Au collisions at RHIC. In d-Au collisions, a suppression in $J/ψ$ production has been observed at the forward rapidity (d direction), at the backward rapidity (Au direction), $J/ψ$ production seems strongly dependent on collisions centrality. The implications of heavy flavor production in cold (d-Au) and hot (Au-Au) nuclear media at RHIC are discu…
We study charm production through dimuon and single muon measurements at forward and backward rapidities in p+p and d+Au collisions with the PHENIX muon detectors. We also compare open charm to $J/ψ$ yields in the forward and backward rapidities in d+Au collisions and study the origin of the large forward and backward asymmetry in open charm production observed by the PHENIX experiment.
In this thesis, we present the measurements of $D^{0}\to Kπ$ at low $p_T$ ($p_T\leq2$ GeV/$c$) and non-photonic electron spectra ($0.9\leq p_T\leq5$ GeV/$c$) from $D^0$ semi-leptonic decay. In addition, we use a newly proposed technique to identify muons from charm decays at low $p_T$. The combination of all these three measurements stringently constrains the total charm production cross-section at mid-rapidity at RHIC. They also allow the extraction of the charmed hadron spectral shape and a study of possible charm radial flow in Au+Au collisions.
An overview of the experimental results on high-pt light hadron production and open charm production is presented. Data on particle production in elementary collisions are compared to next-to-leading order perturbative QCD calculations. Particle production in Au+Au collisions is then compared to this baseline.
We report measurements of charmed hadron production from hadronic ($D^{0}\rightarrow Kπ$) and semileptonic ($μ$ and $e$) decays in 200 GeV Au+Au collisions at RHIC. Analysis of the spectra indicates that charmed hadrons have a different radial flow pattern from light or multi-strange hadrons. Charm cross sections at mid-rapidity are extracted by combining the three independent measurements, covering the transverse momentum range that contributes to $\sim$90% of the integrated cross section. The cross sections scale with number of binary collisions of the initial nucleons, a signature of charm …
Open charm spectra at mid-rapidity from direct reconstruction of $D^{0}\to Kπ$ and indirect electron/positron measurements via charm semileptonic decay in p+p and d+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV are reported. The combined spectra cover open charm transverse momentum range $0.1{}^{<}_{\sim}p_{T}{}^{<}_{\sim}6$ GeV/$c$. The electron spectra show approximate binary scaling between p+p and d+Au collisions. From these two independent analyses, the differential cross section per nucleon-nucleon interaction at mid-rapidity for open charm production at RHIC is $dσ^{NN}_{c\bar{c}}/d…
In this presentation, I discussed a) the charm total cross-section and its comparisons to measurements at other beam energies and pQCD calculations; b) the semileptonic decay of charmed hadrons and the sensitivity of non-photonic leptons to charm quark collective flow and freeze-out; c) semileptonic decayed electron spectrum at high transverse momentum, its comparison to FONLL in p+p and d+Au collisions, and heavy-quark energy loss in Au+Au collisions.
Charm production from the direct reconstruction of $D^0$ ($D^0\to Kπ$ up to 2 GeV/$c$) and indirect lepton measurements via charm semileptonic decays ($c\to e+X$ at 0.9\textless$p_T$\textless5.0 GeV/$c$ and $c\to μ+X$ at 0.17\textless$p_{T}$\textless0.25 GeV/$c$) at $\sqrt{s_{_{NN}}}=200$ GeV Au+Au collisions are analyzed. The transverse momentum ($p_T$) spectra and the nuclear modification factors for $D^0$ and for leptons from heavy flavor decays is presented. Scaling of charm cross-section with number of binary collisions at $\sqrt{s_{_{NN}}}=200$ GeV from d+Au to Au+Au collisions is report…
In this report, we present the measurements of open charm production at mid-rapidity in p+p, d+Au, and Au+Au collisions at RHIC energies. The techniques of direct reconstruction of open charm via its hadronic decay and indirect measurements through its semileptonic decay are discussed. The beam energy dependence of total charm cross section, electron \pt spectra, and their comparisons to theoretical calculations, including NLO pQCD, are presented. The electron spectra in p+p, d+Au, and Au+Au collisions at \srt=200 GeV show significant variation. The open charm absolute cross section at midrapi…
The measurement of quarkonia production in relativistic heavy ion collisions provides a powerful tool for studying the properties of the hot and dense matter created in these collisions. To be really useful, however, such measurements must cover a wide range of quarkonia states and colliding species. The PHENIX experiment at RHIC has successfully measured J/psi, psi-prime, chi_c and Upsilon production in different colliding systems at various energies. In this talk I will present recent results from the PHENIX collaboration on charmonium production in d+Au, Cu+Au and U+U collisions at 200 GeV/…
Heavy-quark production provides a sensitive probe of the gluon structure of nucleons and its modication in nuclei. It is also a key probe of the hot-dense matter created in heavy-ion collisions. We will discuss the physics issues involved, as seen in quarkonia and open heavy-quark production, starting with those observed in proton-proton collisions. Then cold nuclear matter effects on heavy-quark production including shadowing, gluon saturation, energy loss and absorption will be reviewed in the context of recent proton-nucleus and deuteron-nucleus measurements. Next we survey the most recent …
Results from the PHENIX experiment for the first RHIC run with Au-Au collisions at a nucleon-nucleon center-of-mass energy of 130 GeV are presented. The systematic variation with centrality of charged particle multiplicity, transverse energy, elliptic flow, identified particle spectra and yield ratios, and production of charged particles and neutral pions at high transverse momenta are presented. Results on two-pion correlations and electron spectra are also provided, along with a discussion of plans for the second run at RHIC.
Measuring the single transverse spin asymmetry $A_N$ for large $x_F$ Drell-Yan production provides the most robust test of our current theoretical understanding of transverse proton spin structure. This includes a measurement of the predicted sign change of the Sivers function in comparison to that found in SIDIS data. The first year of a feasibility test has been completed to define the requirements for measuring large $x_F$ Drell-Yan production at RHIC. The impact of colliding beams at a third IR at RHIC was found to be negligible and a rich jet-triggered data sample was acquired by AnDY in …
We present a study of charm and beauty isolation based on a data-driven method with recent measurements on heavy flavor hadrons and their decay electrons in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV at RHIC. The individual electron $p_{\rm T}$ spectra, $R_{\rm AA}$ and $v_2$ distributions from charmed and beauty hadron decays are obtained. We find that the electron $R_{\rm AA}$ from beauty hadron decays ($R_{\rm AA}^{\rm b\rightarrow e}$) is suppressed in minimum bias Au+Au collisions but less suppressed compared with that from charmed hadron decays at $p_{\rm T}$ $>$ 3.5 GeV/$c$, whic…
The results from data taken during the last several years at the Relativistic Heavy-Ion Collider (RHIC) will be reviewed in the paper. Several selected topics that further our understanding of constituent quark scaling, jet quenching and color screening effect of heavy quarkonia in the hot dense medium will be presented. Detector upgrades will further probe the properties of Quark Gluon Plasma. Future measurements with upgraded detectors will be presented. The discovery perspectives from future measurements will also be discussed.
Observations by the PHENIX and STAR collaborations suggest that a strongly coupled quark-gluon plasma is produced in heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC). After a brief introduction to heavy-ion physics, measurements of heavy-quark production in heavy-ion collisions and the modification of heavy-quark spectra by the QGP are presented. Measurements of the total charm cross-section in several different collision systems confirm that charm quark-antiquark pairs are produced through parton hard-scattering in the initial stages of the collisions. Non-photonic electrons…
We present the mid-rapidity $(D^{0} + \bar{D^{0}})/2$ yield measured in $\sqrt{s_{NN}}$ = 200 GeV Cu+Cu collisions at RHIC via direct reconstruction through the $Kπ$ decay channel. A charm cross-section is reported and compared to theoretical predictions and to previous RHIC experimental results.
This paper aims at providing an experimental overview of the Strangeness in Quark Matter 2007 Conference
We summarize the recent experimental results of heavy favor physics from the Relativistic Heavy Ion Collider (RHIC) in Brookhaven National Lab (BNL) at Long Island, New York, USA.We will discuss the directly reconstructed open charm mesons as well as electrons from heavy favor hadron decays. The charm and bottom quark production cross-sections have also been measured. We will also discuss JPsi and Upsilon states in p+p and heavy ion collisions. The studies described here were carried out and reported by the STAR and PHENIX collaborations at RHIC.
This is an overview of the results from the first 3 years of RHIC experiments. RHIC is a collider built to accelerate nuclei to center of mass energies of 200 GeV per nucleon for the study of QCD in bulk systems. The most important result so far is the observation of the suppression of high p$_T$ hadrons in central Au-Au collisions followed by the subsequent null experiment where the same suppression was not seen in deuteron-Au collisions. The observed suppression is a final state effect in which a large amount of energy is lost by the fast parton as it penetrates the medium. This observation,…
We make up-to-date QCD predictions for open charm and bottom production at RHIC in nucleon-nucleon collisions at \sqrt{S} = 200 GeV. We also calculate the electron spectrum resulting from heavy flavor decays to allow direct comparison to the data. A rigorous benchmark, including the theoretical uncertainties, is established against which nuclear collision data can be compared to obtain evidence for nuclear effects.
I review the latest heavy flavor measurements at RHIC experiments. Measurements from RHIC together with preliminary results from LHC offer us an opportunity to systematically study the sQGP medium properties. In the end, I will outlook a prospective future on precision heavy flavor measurements with detector upgrades at RHIC.
Recent results on high transverse momentum (pT) hadron production in p+p, d+Au and Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) are reviewed. Comparison of the nuclear modification factors, $R_{dAu}(pT)$ and $R_{AA}(pT)$, demonstrates that the large suppression in central Au+Au collisions is due to strong final-state effects. Theoretical models which incorporate jet quenching via gluon Bremsstrahlung in the dense partonic medium that is expected in central Au+Au collisions at ultra-relativistic energies are shown to reproduce the shape and magnitude of the observed suppressio…
A study of heavy flavor production in different collision systems in various kinematic regions presents an opportunity to probe cold nuclear medium and hot dense matter effects. Results from the PHENIX experiment on $J/ψ$ and open charm production in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$ =200 GeV are presented. The data show strong $J/ψ$ suppression in central AA collisions, similar to NA50 results, and strong suppression in high $p_T$ open charm production. The $J/ψ$ production in Au+Au and d+Au collisions is compared to understand the cold nuclear medium effects. The data show signif…
Measurements at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory have revealed strong modification of the jet structure in high-energy heavy-ion collisions, which can be attributed to the interaction of hard scattered partons with the hot and dense QCD matter. The study of heavy-quark (charm and bottom) production in such collisions provides key tests of parton energy-loss models and, thus, yields profound insight into the properties of the produced matter. The high-pT yield of heavy-flavor decay electrons exhibits an unexpected large suppression. Since those single…
We analyze the transverse momentum distribution of $J/ψ$ mesons produced in Au + Au collisions at the top RHIC energy within a blast-wave model that accounts for a possible inhomogeneity of the charmonium distribution and/or flow fluctuations. The results imply that the transverse momentum spectra of$J/ψ$, $ϕ$ and $Ω$ hadrons measured at the RHIC can be described well if kinetic freeze-out takes place just after chemical freeze-out for these particles.
The PHENIX and STAR Collaborations at the Relativistic Heavy-Ion Collider and ALICE, CMS, ATLAS and LHCb Collaborations at the Large Hadron Collider have measured the production of charmonium and bottonium states as well as open heavy flavor hadrons via their hadronic and semi-leptonic decays at mid-rapidity and in the semi-muonic decay channel at forward rapidity in pp, p--A and A--A collisions in an energy domain that ranges from $\sqrt{s}$ = 0.2 TeV to $\sqrt{s}$ = 13 TeV in pp collisions and from $\sqrt{s_{\rm NN}}$ = 0.2 TeV to $\sqrt{s_{\rm NN}}$ = 5.02 TeV in A--A collisions. In this co…
Charmonium suppression in hot and dense nuclear matter has been argued to be a signature for the production of the quark gluon plasma (QGP). In order to search for this effect in heavy ion collisions one must have a clear understanding of all the factors that can contribute to such a suppression. These may include shadowing of the partons in a nuclear environment, breakup of a correlated $c-\bar{c}$ pair as it traverses the nuclear fragment, suppression of feed-down from higher mass states as well as other initial state interactions. In order to disentangle these effects one must measure charm…
Quantum Chromodynamics (QCD) is a basic gauge field theory to describe strong interactions. Lattice QCD calculations predict a phase transition from hadronic matter to a deconfined, locally thermalized Quark-Gluon Plasma (QGP) state at high temperature and small baryon density. Plenty of exciting results from RHIC experiments in the first three years have demonstrated that a hot dense matter with strong collective motion which cannot be described with hadronic degrees of freedom was created at RHIC. Charm quarks are believed to be mostly created from initial gluon fusion in heavy ion collision…
A study of elliptic flow of open charm mesons, $D^0$ and $D_S ^\pm$ using quark coalescence as a mechanism of hadronization of heavy quarks implemented in conjunction with A Multi Phase Transport (AMPT) model has been presented. We have studied the transverse momentum dependence of the elliptic flow parameter at mid-rapidity ($|y|$ $<$ 1.0) for Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV (RHIC) and Pb+Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV (LHC) for different values of partonic interaction cross-section and QCD coupling constant. We have compared our calculations with the experimentally…
The complete understanding of the basic constituents of hadrons and the hadronic dynamics at high energies are two of the main challenges for the theory of strong interactions. In particular, the existence of intrinsic heavy quark components in the hadron wave function must be confirmed (or disproved). In this paper we propose a new mechanism for the production of $D$-mesons at forward rapidities based on the Color Glass Condensate (CGC) formalism and demonstrate that the resulting transverse momentum spectra are strongly dependent on the behavior of the charm distribution at large Bjorken $x$…
Following on the discovery of a strongly interacting quark-gluon plasma (QGP) at RHIC, a program of detailed quarkonia measurements is crucial to understanding the nature of deconfinement. Lattice QCD calculations suggest a sequential melting of the quarkonia states in the deconfined medium. Such a melting would lead to a suppression in the measured charmonium and bottomonium yields. However, distinguishing a true suppression from shadowing, absorption, and recombination effects requires detailed measurements of the charmonium states (J/psi, psi', and chi_c) and bottomonium states (Y(1S), Y(2S…
We have discussed single and central diffractive production of $c \bar c$ pairs in the Ingelman-Schlein model. In these calculations we have included diffractive parton distributions obtained by the H1 collaboration at HERA and absorption effects neglected in some early calculations in the literature. The absorption effects which are responsible for the naive Regge factorization breaking cause that the cross section for diffractive processes is much smaller than that for the fully inclusive case, but could be measured at RHIC and LHC by imposing special condition on rapidity gaps. We discuss a…
We report on measurements of open charm production through both hadronic and semi-leptonic decay channels in $\sqrt{s_{NN}}$ = 200 GeV heavy ion collision at the STAR experiment at RHIC. We compare experimental results to theoretical predictions from pQCD. The open charm $R_{AA}$ is also presented as evidence of possible medium-induced energy loss.
Heavy Flavors and Quarkonia at RHIC
本文综述RHIC前二十年200 GeV碰撞中PHENIX与STAR实验的重味及夸克偶素测量，揭示QGP性质，展望其与未来EIC的协同研究前景。
We describe the propagation of charm quarks in the quark-gluon plasma (QGP) by means of a Boltzmann transport approach. Non-perturbative interaction between heavy quarks and light quarks have been taken into account through a quasi-particle approach in which light partons are dressed with thermal masses tuned to lQCD thermodynamics. Such a model is able to describe the main feature of the non-perturbative dynamics: the enhancement of the interaction strength near $T_c$. We show that the resulting charm in-medium evolution is able to correctly predict simultaneously the nuclear suppression fact…
A brief review of BRAHMS measurements of bulk particle production in RHIC Au+Au collisions at $\sqrt{s_{NN}}=200GeV$ is presented, together with some discussion of baryon number transport. Intermediate $p_{T}$ measurements in different collision systems (Au+Au, d+Au and p+p) are also discussed in the context of jet quenching and saturation of the gluon density in Au ions at RHIC energies. This report also includes preliminary results for identified particles at forward rapidities in d+Au and Au+Au collisions.
Flow measurements of multi-strange baryons from Au + Au collisions at RHIC energies demonstrate that collectivity develops before hadronization, among partons. To pin down the partonic EOS of matter produced at RHIC, the status of thermalization in such collisions has to be addressed. We propose to measure collective flow of heavy-flavor quarks, e.g. charm quarks, as an indicator of thermalization of light flavors ($u,d,s$). The completion of the time of flight barrel and the proposed upgrade with a $μ$Vertex detector for heavy-flavor identification in STAR are well suited for achieving these …
The measurement of electrons from semi-leptonic decay of heavy flavor in $p+p$ collisions at $\sqrt{s}$=200 GeV has been carried out with the PHENIX detector in the RHIC Year-2005 and Year-2006 run. This measurement provides a good test of the perturbative QCD and the important base line to study the medium created in Au+Au collisions at RHIC. The behavior of bottom in the medium is expected to be largely different from that of charm. Therefore, the determination of the fraction of bottom in the electrons from heavy flavor is necessary to understand the behavior of heavy quarks in the matter. …
Results on physics at RHIC using outgoing leptons and photons will be presented from Au+Au collisions at nucleon-nucleon c.m. energies $\sqrt{s_{NN}}=130$ and 200 GeV and from p-p collisions at $\sqrt{s}=200$ GeV. Introduction and motivation will be presented both from the theoretical and experimental perspectives. Topics include open charm production via single $e^{\pm}$, $J/Ψ\to e^+ + e^-$, $μ^+ + μ^-$ and inclusive photon production.
Ultra-peripheral collisions (UPCs) of ions allow us to study photonuclear and two-photon interactions at energies above those available at fixed target accelerators. For heavy ions, the couplings are large enough so that multi-photon interactions are possible, and higher order corrections are expected to be significant. In this writeup, I present some recent UPC results from the Relativistic Heavy Ion Collider (RHIC), and discuss some future prospects. I also draw parallels between UPC data and that expected at an electron-ion collider (EIC), and show how UPCs are a useful lead-in to EIC physi…
sPHENIX measurement of Open-Charm Baryon-to-Meson Ratios in $p$+$p$ collisions at RHIC
sPHENIX利用高统计样本研究RHIC上$ p $+$ p $碰撞中开放charm重子-介子比值，首次探索重子hadronization机制和奇异-轻味介子比。
We have developed a silicon pixel detector to enhance the physics capabilities of the PHENIX experiment. This detector, consisting of two layers of sensors, will be installed around the beam pipe at the collision point and covers a pseudo-rapidity of | η| < 1.2 and an azimuth angle of | ϕ| ~ 2π. The detector uses 200 um thick silicon sensors and readout chips developed for the ALICE experiment. In order to meet the PHENIX DAQ readout requirements, it is necessary to read out 4 readout chips in parallel. The physics goals of PHENIX require that radiation thickness of the detector be minimized. …
With large acceptance and excellent particle identification, STAR is one of the best mid-rapidity collider experiments for studying high-energy nuclear collisions. The STAR experiment provides full information on initial conditions, properties of the hot and dense medium as well as the properties at freeze-out. In Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV, STAR's focus is on the nature of the sQGP produced at RHIC. In order to explore the properties of the QCD phase diagram, since 2010, the experiment has collected sizable data sets of Au+Au collisions at the lower collision energy region …
The J/psi is considered to be among the most important probes for the deconfined quark gluon plasma (QGP) created by relativistic heavy ion collisions. While the J/psi is thought to dissociate in the QGP by Debye color screening, there are competing effects from cold nuclear matter (CNM), feed-downs from excited charmonia (chi_c and psi') and bottom quarks, and regeneration from uncorrelated charm quarks. Measurements that can provide information to disentangle these effects are presented in this paper.
Heavy quarks are produced through initial hard scatterings and they are affected by the hot and dense medium created in heavy-ion collisions throughout its whole evolution. Due to their heavy mass, charm quarks are expected to thermalize much more slowly than light flavor quarks. The charm quark flow is a unique tool to study the extent of thermalization of the bulk medium dominated by light quarks and gluons. At high $p_T$, D meson azimuthal anisotropy is sensitive to the path length dependence of charm quark energy loss in the medium, which offers new insights into heavy quark energy loss me…
A kinetic-rate equation approach in a thermally expanding medium is employed to calculate the evolution of charmonium and bottomonium distributions in heavy-ion collisions. The equilibrium properties of the quarkonia are taken from in-medium spectral functions which are schematically constrained by euclidean correlators from lattice QCD. The initial conditions for the rate equation (heavy-flavor cross sections, nuclear absorption) and the thermal evolution are constrained by data as available. After fixing two free parameters to describe charmonium data at SPS and RHIC, the predictions for LHC…
We update the study of the total Psi and Upsilon production cross section in proton-proton collisions at RHIC energies using the QCD-based Color-Singlet (CS) Model, including next-to-leading order partonic matrix elements. We also include charm-quark initiated processes which appear at leading order in alpha_s, but which have so far been overlooked in such studies. Contrary to earlier claims, we show that the CS yield is consistent with measurements over a broad range of J/Psi rapidities. We also find that charm-quark initiated processes, including both intrinsic and sea-like charm components,…
Inclusive transverse momentum spectra of single electrons from Au+Au collisions have been measured at $\sqrt{s_{NN}}$ = 130 GeV and 200 GeV at midrapidity by the PHENIX experiment at RHIC. After subtraction of background from photon conversions and light hadron decays, the spectra appear consistent with semileptonic decays of charmed particles.
Experiments using heavy ion collisions at ultrarelativistic energies aim to explore the QCD phase transition and map out the QCD phase diagram. A wealth of remarkable results in this field have been reported recently, for example the Upsilon suppression discovered recently. We discuss recent results from the STAR experiment focusing on strangeness, charm and beauty production.
Heavy flavor and quarkona production are important hard probes to test the Quantum Chromodynamics (QCD) and measure the properties of the Quark Gluon Plasma (QGP) created in high energy heavy ion collisions. The new PHENIX mid- and forward-rapidity silicon vertex detectors provide precise Distance of Closest Approach (DCA) determination, allowing charm and bottom yields identification, and improve di-muon mass resolution for charmonia studies. The relative $ψ(2S)$ over $J/ψ$(1S) yields measured in $p$+$p$, $p$+Al and $p$+Au data at $\sqrt{s}=$200 GeV help us to understand final state effects o…
Fluctuations of conserved quantities, such as baryon, electric charge and strangeness number, are sensitive observables in relativistic heavy-ion collisions to probe the QCD phase transition and search for the QCD critical point. In this paper, we review the experimental measurements of the cumulants (up to fourth order) of event-by-event net-proton (proxy for net-baryon), net-charge and net-kaon (proxy for net-strangeness) multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}=7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, 200$ GeV from the first phase of beam energy scan program at the Relat…
We review recent progress in applying relativistic hydrodynamics to the modeling of heavy-ion collisions at RHIC and LHC, with emphasis on anisotropic flow and flow fluctuations.
Experiments with gold-gold collisions at RHIC have revealed (i) stronger suppression of charmonium production at forward rapidity than at midrapidity and (ii) the similarity between the suppression degrees at RHIC and SPS energies. To describe these findings we employ the model that includes nuclear shadowing effects, calculated within the Glauber-Gribov theory, rapidity-dependent absorptive mechanism, caused by energy-momentum conservation, and dissociation and recombination of the charmonium due to interaction with co-moving matter. The free parameters of the model are tuned and fixed by com…
We study the effect of thermal charm production on charmonium regeneration in high energy nuclear collisions. By solving the kinetic equations for charm quark and charmonium distributions in Pb+Pb collisions, we calculate the global and differential nuclear modification factors $R_{AA}(N_{part})$ and $R{AA}(p_t)$ for $J/Ψ$s. Due to the thermal charm production in hot medium, the charmonium production source changes from the initially created charm quarks at SPS, RHIC and LHC to the thermally produced charm quarks at Future Circular Collider (FCC), and the $J/Ψ$ suppression ($R_{AA}<1$) observe…
We report recent results from a multiphase transport (AMPT) model on the azimuthal anisotropies of particle momentum distributions in heavy ion collisions at the Relativistic Heavy Ion Collider. These include higher-order anisotropic flows and their scaling, the rapidity dependence of anisotropic flows, and the elliptic flow of charm quarks.
Thermalization and collective flow of charm (c) and bottom (b) quarks are evaluated from elastic parton scattering via "D"- and "B"-meson resonances in an expanding, strongly interacting quark-gluon plasma at RHIC. Pertinent drag and diffusion coefficients are implemented into a relativistic Langevin simulation to compute transverse-momentum spectra and azimuthal flow asymmetries (v_2) of c- and b-quarks. Upon hadronization (including coalescence and fragmentation) and semileptonic D- and B-decays, the resulting electron spectra (R_{AA} and v_2) are compared to recent RHIC data.
We investigate the production of psi(2S) in nuclear collisions at RHIC and LHC energies. We first address charmonium production in 200 GeV d-Au collisions at RHIC; the strong suppression of psi' mesons observed in these reactions indicates mechanisms beyond initial cold nuclear matter effects. We find that a more complete treatment of hadronic dissociation reactions leads to appreciable psi' suppression in the hadronic medium of an expanding fireball background for d-Au collisions. When implementing the updated hadronic reaction rates into a fireball for 2.76 TeV Pb-Pb collisions at LHC, the r…
We propose an empirical model to determine the form of energy loss of charm quarks due to multiple scatterings in quark gluon plasma by demanding a good description of production of D mesons and non-photonic electrons in relativistic collision of heavy nuclei at RHIC and LHC energies. Best results are obtained when we approximate the momentum loss per collision $Δp_T \propto α\, p_T$, where $α$ is a constant depending on the centrality and the centre of mass energy. Comparing our results with those obtained earlier for drag coefficients estimated using Langevin equation for heavy quarks we fin…
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