超相对论性重离子碰撞中的熵  

The Entropy in Ultrarelativistic Heavy-ion Collisions

作　　者：李盘林[1] 李志良[1] 施心慧[1] 

机构地区：[1]苏州铁道师范学院物理系,上海大学数学系,青岛海洋大学数学系

出　　处：《苏州科技学院学报（自然科学版）》1995年第2期5-12,共8页Journal of Suzhou University of Science and Technology （Natural Science Edition）

摘　　要：众所周知，在相对论热力学中熵是一个Ｌｏｒｅｎｔｚ不变量。在超相对论能量下的重离子碰撞中，体系的熵又和完全的状态方程有关，并与发射的不同种类的粒子的比率相应。因此我们选定熵作为一个膨胀夸克－胶子等离子体的演化参数，并建立包含膨胀和不可逆味动力学的熵方程；从带有源项的动力学方程和热巨配分函数的关系，带有熵产生项的熵方程被等同地导出，在源项中，我们试图充分地包含所有的粒子，即除了少量强子是在碰撞初产生的外，主要是来自于体系膨胀期间夸克－胶子等离子体相变的贡献，夸克－胶子相向强子相的演化是采用了强唯象学模型来描述的。源的区域在双曲线ｔ２－Ｘ２＝τ＝１（ｆｍ／ｃ）以上，在该区域内，和，在源区域以外，ＴμＳμ＝０，体系仅作绝热膨胀。自此人们清晰地看到，在源区域内，熵是如何被强子和重子物质产生出来的。相变过程中的熵密度的演化是通过对熵方程积分的数值计算得到的，结果能够用来评价获得夸克－胶子等离子体的可能性，也一样可用以讨论对它的诊断。Abstract:It is known that t an entropy is a Lorentz invariable in relativistic thermo dynamics The entropy of'the system is also related to the complete equation of state and is reflected in the ratios of different particle species emitted in the collisions of heavy ions at ultrarelativistic energy ,Tius the entropy is chosen as an evolution parameter of the system of an expansion quark-gluon plasma and an entropy equation including expansion and irreversible flavour kinetics is set up.From hydrodynamic equations with source terms and the thermal grand canonical ensemble relation, the entripy equation with an entropy generation terms is derived identically,In thesource terms andσ,for our purpose they are sufficient to include all particles i e.besides small produced hadronic particles in the primaru collisions,a main part of the contribution will be provided by the transition of the quark-gluon plasma phase during the expansion of the system,A string phenonenology,is used to describe the evolution of quark-gluon phase towards all the hadrontic phase,The source region,a nd σ≠0,lies over hyperbolat2-x2=τ0=1 (fm/c).Outside the scarce region TaμSμ'= 0 and the system expands aniabatically Then one sees explicitly that how the entropy is generated in the sine roe region by hadromic matter and baryon number production Theevolution of the entropy density of the process in the phase transition was calculated by numerically i,itegratinAr the entropy equation.the results can be used to assess the possibility of attaining the quark-gluon plasma phase as well as to discuss its diagnosis.

关 键 词：超相对论 夸克─胶子等离子体 Lorentz不变量 熵方程 

分 类 号：O414[理学—理论物理] O572[理学—物理]