Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThermal Description of Particle Production in Au-Au Collisions at STAR Energies
185
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The hadron ratios measured in central Au-Au collisions are analysed by means of Hadron Resonance Gas (HRG) model over a wide range of nucleon-nucleon center-of-mass energies ranging from 7.7 to 200 GeV as offered by the STAR Beam Energy Scan I (BES-I). We restrict the discussion on STAR BES-I, because of large statistics and over all homogeneity of STAR measurements (one detector) against previous experiments. Over the last three decades, various heavy-ion experiments utilizing different detectors (different certainties) have been carried out. Regularities in produced particles at different energies haven been studied. The temperature and baryon chemical potential are deduced from fits of experimental ratios to thermal model calculations assuming chemical equilibrium. We find that the resulting freeze-out parameters using single hard-core value and point-like constituents of HRG are identical. This implies that the excluded-volume comes up with no effect on the extracted parameters. We compare the results with other studies and with the lattice QCD calculations. Various freeze-out conditions are confronted with the resulting data set. The effect of feed-down contribution from week decay and of including new resonances are also analysed. At vanishing chemical potential, a limiting temperature was estimated as T=158.5 MeV with 3 MeV uncertainty.
rate research
Read More
(Abstract is abridged for arXiv.) Identified mid-rapidity particle spectra and freeze-out properties are presented for 200 GeV pp, 200 GeV dAu and 62.4 GeV Au-Au collisions, measured in the STAR-TPC. Evolution of the identified particle spectra ($pi^{pm}$, $K^{pm}$, p and $overline{p}$) with charged particle multiplicity and event centrality is investigated in detail. Thermal model fits to the measured particle ratios yield a chemical freeze-out temperature $sim$ 155 MeV in 200 GeV pp, 200 GeV dAu and 62.4 GeV Au-Au collisions. The extracted chemical freeze-out temperature is close to the critical phase transition temperature predicted by lattice QCD calculations. The kinetic freeze-out temperature extracted from hydrodynamically motivated blast-wave models shows a continuous drop from pp, dAu and peripheral to central Au-Au collisions, while the transverse flow velocity increases from $sim$ 0.2 in pp to $sim$ 0.6 in central 200 GeV Au-Au collisions. The kinetic freeze-out parameters in 62.4 GeV and 200 GeV Au-Au collisions seem to be governed only by event multiplicity/centrality. In order to study the effect of resonance decays on the kinetic freeze-out parameters, the data are fitted with the blast-wave model including resonances. It is found that the thus extracted parameters are consistent with those obtained without including resonances, the resonance decays do not modify the spectral shapes significantly in the measured $p_{T}$ region in STAR.
The charged particles produced in heavy ion collisions consist of two parts: One is from the freeze-out of hot and dense matter formed in collisions. The other is from the leading particles. In this paper, the hot and dense matter is assumed to expand according to the hydrodynamic model including phase transition and decouples into particles via the prescription of Cooper-Frye. The leading particles are as usual supposed to have Gaussian rapidity distributions with the number equaling that of participants. The investigations of this paper show that, unlike low energy situations, the leading particles are essential in describing the pseudorapidity distributions of charged particles produced in high energy heavy ion collisions. This might be due to the different transparencies of nuclei at different energies.
We present a study of three-particle correlations among a trigger particle and two associated particles in Au + Au collisions at $sqrt{s_{NN}}$ = 200 GeV using a multi-phase transport model (AMPT) with both partonic and hadronic interactions. We found that three-particle correlation densities in different angular directions with respect to the triggered particle (`center, `cone, `deflected, `near and `near-away) increase with the number of participants. The ratio of `deflected to `cone density approaches to 1.0 with the increasing of number of participants, which indicates that partonic Mach-like shock waves can be produced by strong parton cascades in central Au+Au collisions.
We study the collision energy dependence of (anti-)deuteron and (anti-)triton production in the most central Au+Au collisions at $sqrt{s_mathrm{NN}}=$ 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV, using the nucleon coalescence model. The needed phase-space distribution of nucleons at the kinetic freeze-out is generated from a new 3D hybrid dynamical model (texttt{iEBE-MUSIC}) by using a smooth crossover equation of state (EoS) without a QCD critical point. Our model calculations predict that the coalescence parameters of (anti-)deuteron ($B_2(d)$ and $B_2(bar{d})$) decrease monotonically as the collision energy increases, and the light nuclei yield ratio $N_t N_p/N_d^2$ remains approximately a constant with respect to the collision energy. These calculated observables fail to reproduce the non-monotonic behavior of the corresponding data from the STAR Collaboration. Without including any effects of the critical point in our model, our results serve as the baseline predictions for the yields of light nuclei in the search for the possible QCD critical points from the experimental beam energy scan of heavy ion collisions.
We analyze the transverse momentum distribution of $J/psi$ 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$J/psi$, $phi$ and $Omega$ hadrons measured at the RHIC can be described well if kinetic freeze-out takes place just after chemical freeze-out for these particles.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
