Study of Pion-Source Size in Relativistic Nuclear Collisions

The BoseEinstein correlation of pion pairs is calculated using the space-time and four-momentum distributions Gom an event generator URASiMA for 200 AGeV/c Pb + Pb and compared to pion correlation measurement from CERN experiment of NA44. The spacetime distributions of the simulated pion-emitting source are also analyzed.     

Charged Multiplicity Density and Number of Participant Nucleons in Relativistic Nuclear Collisions

The energy and centrality dependencies of charged particle pseudorapidity density in relativistic nuclearcollisions were studied using a hadron and string cascade model, JPCIAE. Both the relativistic p+p experimental dataand the PHOBOS and PHENIX Au+Au data at RHIC energy could be fairly reproduced within the framework ofJPCIAE model and without retuning the model parameters. The predictions for Pb + Pb collisions at the LHC energywere also given. We computed the participant nucleon distributions using different methods. It was found that thenumber of participant nucleons is not a well defined variable both experimentally and theoretically. Thus it may beinappropriate to use the charged particle pseudorapidity density per participant pair .as a function of the number ofparticipant nucleons for distinguishing various theoretical models.     

Some Possible Asymmetry Effects of Nuclear Matter in Relativistic Heavy Ion Collisions

The asymmetry dependence of nuclear incompraeaibility and that of nuclear critical temperature are calculated baaed on a Thomas-Fermi model with Seyler-Blanchard interaction. It is found that the asymmetry effects are big enough to allow for checking the existence of these effects in relativistic heavy-ion collision experiments.     

Some Aspects of Nuclear Structure in Relativistic Approach

The nucleon effective interaction in the nuclear medium is investigated in the framework of the DiracBrueckner-Hartree-Fock (DBHF) approach. A new decomposition of the Dirac structure of nucleon self-energy in the DBHF is adopted for asymmetric nuclear matter. The properties of finite nuclei are investigated with the nucleon effective interaction. The agreement with the experimental data is satisfactory. The relativistic microscopic optical potential in asymmetric nuclear matter is investigated in the DBHF approach. The proton scattering from nuclei is calculated and compared with the experimental data. A proper treatment of the resonant continuum for exotic nuclei is studied. The width effect of the resonant continuum on the pairing correlation is discussed. The quasiparticle relativistic random phase approximation based on the relativistic mean-field ground state in the response function formalism is also addressed.     

Some Aspects of Nuclear Structure in Relativistic Approach

The nucleon effective interaction in the nuclear medium is investigated in the framework of the DiracBrueckner-Hartree-Fock (DBHF) approach. A new decomposition of the Dirac structure of nucleon self-energy in the DBHF is adopted for asymmetric nuclear matter. The properties of finite nuclei are investigated with the nucleon effective interaction. The agreement with the experimental data is satisfactory. The relativistic microscopic optical potential in asymmetric nuclear matter is investigated in the DBHF approach. The proton scattering from nuclei is calculated and compared with the experimental data. A proper treatment of the resonant continuum for exotic nuclei is studied. The width effect of the resonant continuum on the pairing correlation is discussed. The quasiparticle relativistic random phase approximation based on the relativistic mean-field ground state in the response function formalism is also addressed.     

Analysis of Collective Flow in High Energy Heavy-Ion Collisions in the Relativistic VUU Approach

We have calculated the collective flow for Ar+KCl collisions of 1200 MeV/A by using the relativistic Vlasov-Uehling- Uhlenbeck (VUU) equation based on the QHD-I model of Walecka. The tensitivity of flow characterized by C(ψ)a nd (P_x(Y))to mean field and in-medium NN scattering cross section is studied. It is found that the azimuthal correlation function C(ψ) is reduced dramatically after inserting the collision term and then varies very slowly between NN cross sections from σ = 10 mb to 55 mb and reaches the minimum at σ = 35 mb, while the in-plane mean transverse momentum (P_x(Y))in creases slowly all the way from σ = 0 mb to 55 mb. The collective flow is very sensitive to the momentum dependence (indicated by the effective mass m⁰) of the mean field and less sensitive to the compression modulus K and the cross sections from σ = 10 mb to 55 mb. The numerical results were compared with the experimental data, and we found that the agreement for both (P_x(Y)) and C(ψ) can be reached with the same set of mean field parameters as well as the appropriate NN cross section in collision terms.     

相对论重离子碰撞的趋平衡问题

从相对论ＢＵＵ理论出发,研究了１ＧｅＶ／ｕ能区重离子碰撞全局和局域平衡性质．研究结果表明,在该能区平均场对反应动力学过程仍有相当的作用;对有限核系统的反应动力学过程的时间演化的研究表明,有限核系统未能达到全局平衡,在中心区基本达到局域平衡．因而在该能区的重离子碰撞中引入完全热平衡概念时,需谨慎考虑．The equilibration in relativistic heavy ion collisions for systems 16 O+ 16 O, 40 Ca+ 40 La and 139 La+ 139 La is studied with RBUU theory. We have found that the mean field still plays a role in addition to the collision term in the equilibration process in relativistic heavy ion collisions at energy around 1 GeV/u. For finite systems, the systems do not reach complete equilibrium. But at the center zone, the local equilibrium is almost reached.     

Vorticity and Particle Polarization in Relativistic Heavy-Ion Collisions

Physics of Atomic Nuclei - We review studies of vortical motion and the resulting global polarization of $$Lambda$$ and $$bar{Lambda}$$ hyperons in heavy-ion collisions, in particular, within...     

Relativistic Mean-Field Approach to Infinite Nuclear Matter and Neutron Star

The properties of infinite nuclear matter and neutron star are studied theoretically in relativistic mean-field (RMF) approach with three typical parameter sets NL1, NL-SH and TM1. It is found that all these new RMF parameter sets can very satisfactorily reproduce the properties of high density matter. Among these parameter sets, TM1, with a nonlinear ω term, reproduces a slightly smaller energy, piessure and neutron star mass than NL-SH and NL1. The ρ meson field has a large influence on the properties of neutron star and infinite nuclear matter. A detailed discussion for the significance of numerical results is also given.     

Search for Tetraquarks in Relativistic Heavy-Ion Collisions

Tetraquarks can be produced in relativistic heavy-ion collision. The yield of this kind of tetraquarks can increase significantly soon as the formation of QGP after the collision. If there is no phase transition after collision, the upper bound of the production of this four-quark states can be estimated from the free hadronic gas model for nuclearmatter. The relative yield ratio of tetraquark cs(s)(s) to Ω is less than 0.0164.     

Search for Tetraquarks in Relativistic Heavy-Ion Collisions

Tetraquarks can be produced in relativistic heavy-ion collision. The yield of this kind of tetraquarks can increase significantly soon as the formation of QGP after the collision. If there is no phase transition after collision, the upper bound of the production of this four-quark states can be estimated from the free hadronlc gas model for nuclear matter. The relative yield ratio of tetraquark cs^-s^-s to Ω is less than 0.0164.     

The Effect of Secondary Collisions in the Rapidity Distribution in Relativistic Heavy Ion Collisions

Based on the participant model the effect of secondary collisions in relativistic heavy ion collisions is analyzed by introducing additional contributions in fragmentation regions. The rapidity distributions of n of NA35 and WA80 groups are well reproduced. Special improvement is shown in the target fragmentation region.     

相对论重离子碰撞中的重味产生

重味粒子是新的物质形态——夸克胶子等离子体的敏感探针。 利用相对论流体力学描述夸克胶子等离子体的时空演化, 采用输运方程模拟重味粒子在夸克胶子等离子体中的运动, 既考虑重味粒子的热胶子离解, 也通过细致平衡原理包含重味粒子在热密媒质中的重产生。 正是由于离解与重产生之间的竞争以及竞争对于碰撞能量、 横动量和快度的依赖性, 自然解释了在RHIC能区的J/ψ疑难, 预言了在LHC能区由于重产生取得主导地位, J/ψ的核修正因子在中心和半中心碰撞中将随着参与反应核子数的增大而升高, 同时其平均横动量会受到强烈的压低。 Heavy quarkonium is a sensitive signature of the new state of matter-quark gluon plasma produced in high energy nuclear collisions. We describe the space time evolution of the quark gluon plasma by relativistic hydrodynamic equations and the quarkonium motion by transport equation. We found that the competition between the gluon dissociation and regeneration can explain naturally the J/ψ puzzles at RHIC energy. We predict the increase of the nuclear modification factor in semi central and central collisions and the related transverse momentum suppression at LHC energy.     

Observation of the Antimatter Nuclei in Relativistic Heavy Ion Collisions

Recently antimatter hyper-triton nuclei ${(_{\bar{\Lambda}}^3\bar{H})}$ and antimatter helium nuclei ${(_2^4\bar{He})}$ are discovered with the Solenoidal Tracker At Rhic detector in relativistic heavy ion collisions at Relativistic Heavy Ion Collider (RHIC) (STAR Collaboration in Science 328(5974):58–62, 2010; STAR Collaboration in Nature 473:353–356, 2011). In this presentation, discoveries of antimatter particle are historically scanned and the recent observations at RHIC are reported in details as well as potential possibilities of discovery of antimatter nuclei at ALICE.     

Shell-model-like Approach (SLAP) for the Nuclear Properties in Relativistic Mean field Theory

A Shell-model-like approach suggested to treat the pairing correlations in relativistic mean field theory is introduced, in which the occupancies thus obtained have been iterated back into the densities. The formalism and numerical techniques are given in detail. As examples, the ground state properties and low-lying excited states for Ne isotopes are studied. The results thus obtained are compared with the data available. The binding energies, the odd–even staggering, as well as the tendency for the change of the shapes in Ne isotopes are correctly reproduced.     

Full and Partial Thermalization of Nucleons in Relativistic Nucleus-Nucleus Collisions

We propose a mechanism of thermalization of nucleons in relativistic nucleus-nucleus collisions. Our model belongs, to a certain degree, to the transport ones; we consider the evolution of the system, but we parametrize this development by the number of collisions of every particle in the system rather than by the time variable. We based on the assumption that the nucleon momentum transfer after several nucleon-nucleon (-hadron) collisions becomes a random quantity driven by a proper distribution.