Multiphase transport model for relativistic nuclear collisions

Abstract

To study heavy ion collisions at energies available from the Relativistic Heavy Ion Collider ͑RHIC͒, we have developed a multiphase transport model that includes both initial partonic and final hadronic interactions. Specifically, the Zhang's parton cascade ͑ZPC͒ model, which uses as input the parton distribution from the heavy ion jet interaction generator ͑HIJING͒ model, is extended to include the quark-gluon-to-hadronicmatter transition and also final-state hadronic interactions based on a relativistic transport ͑ART͒ model. Predictions of the model for central Au on Au collisions at RHIC are reported.PACS number͑s͒: 25.75. Ϫq, 24.10.Lx, 24.10.Jv The beginning of experiments at the Relativistic Heavy Ion Collider ͑RHIC͒ this year will start an exciting new era in nuclear and particle physics. The estimated high energy density in central heavy ion collisions at RHIC is expected to lead to the formation of a large region of deconfined matter of quarks and gluons, the quark gluon plasma ͑QGP͒. This would give us the opportunity to study the properties of the QGP and its transition to hadronic matter, which would then shed light on the underlying fundamental theory of strong interactions, quantum chromodynamics ͑QCD͒.Because of the complexity of heavy ion collision dynamics, Monte Carlo event generators are needed to relate the experimental observations to the underlying theory. This has already been shown to be the case in heavy ion collisions at existing accelerators such as the SIS, AGS, and SPS ͓1-6͔. As minijet production is expected to play an important role at RHIC energies ͓7͔, models for partonic transport have been studied ͓8,9͔. Furthermore, transport models that include both partonic and hadronic degrees of freedom are being developed ͓10,11͔. We have recently also developed such a multiphase transport ͑AMPT͒ model. It starts from initial conditions that are motivated by perturbative QCD and incorporates the subsequent partonic and hadronic spacetime evolution. In particular, we have used the heavy ion jet interaction generator ͑HIJING͒ model ͓7͔ to generate the initial phase space distribution of partons and the Zhang's parton cascade ͑ZPC͒ model ͓9͔ to follow their rescatterings. A modified HIJING fragmentation scheme is then introduced for treating the hadronization of the partonic matter. The evolution of the resulting hadron system is treated in the framework of a relativistic transport ͑ART͒ model ͓2͔. In this paper, we shall describe this new multiphase transport model and show its predictions for central Au-on-Au collisions at RHIC.In the AMPT model, the initial parton momentum distribution is generated from the HIJING model, which is a Monte Carlo event generator for hadron-hadron, hadronnucleus, and nucleus-nucleus collisions. The HIJING model treats a nucleus-nucleus collision as a superposition of binary nucleon-nucleon collisions. For each pair of nucleons, the impact parameter is determined using the nucleon transverse positions generated from a Woods-Saxon nuclear density distributio...

Higher harmonic flow coefficients of identified hadrons in Pb-Pb collisions at s N N = 2.76 $$ \sqrt{s_{\mathrm{NN}}}=2.76 $$ TeV

“…Section 6.3 presents the mass dependence of v sub n (p T ) which is followed by a discussion about the scaling properties of different flow harmonics in different centrality intervals. In section 6.5, two models, namely iEBE-VISHNU [49] and A Multi Phase Transport model (AMPT) [50][51][52], are compared with the experimental measurements. Note that the same data will be shown in different representations in the following sections to highlight the various physics implications of the measurements.…”

“…In particular in [23] it was shown that a hybrid model that couples the hydrodynamical expansion of the fireball to a hadronic cascade model describing the finalstate hadronic interactions is able to reproduce the basic features of the measurements at low values of p T . In parallel, various other models that incorporate a different description of the dynamical evolution of the system, such as AMPT, are also able to describe some of the main features of measurements of azimuthal anisotropy [50][51][52]. In this section, these two different theoretical approaches will be confronted with the experimental measurements.…”

Anisotropic flow inCu+Aucollisions atsNN=200GeV

“…Final-state scatterings among hadrons are then modeled by a relativistic transport (ART) model [31]. The default AMPT model [20] has been quite successful in describing measured rapidity distributions of charge particles, particle to antiparticle ratios, and spectra of low transverse momentum pions and kaons [21] in heavy-ion collisions at the Super Proton Synchrotron (SPS) and RHIC. It has also been useful in understanding the production of J /ψ [25] and multistrange baryons [26] in these collisions.…”

“…The AMPT model [20,21,[25][26][27]] is a hybrid model that uses minijet partons from hard processes and strings from soft processes in the Heavy Ion Jet Interaction Generator (HIJING) model [28] as the initial conditions for modeling heavy-ion collisions at ultra-relativistic energies. The time evolution of resulting minijet partons is described by Zhang's parton cascade (ZPC) [29] model.…”

“…In the present work, we use a multiphase transport (AMPT) model, which includes both initial partonic and final hadronic interactions [20,21], to study the anisotropic flows v 1 , v 2 , v 3 , and v 4 of charged hadrons in asymmetric Cu + Au collisions at √ s = 200A GeV at RHIC. Use is made of both the default version and the version with string melting, that is, a version allowing hadrons that are expected to be formed from initial strings to convert to their valence quarks and antiquarks [10,22,23].…”