PNJL模型下手征相变的临界指数  

Critical Exponents of the Chiral Phase Transition in the PNJL Model

作　　者：高雪艳 贺伟博 邵国运 GAO Xueyan;HE Weibo;SHAO Guoyun(School of Physics,Xi’an Jiaotong University,Xi’an,710049,China;MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter,Xi’an Jiaotong University,Xi’an,710049,China)

机构地区：[1]西安交通大学物理学院,西安710049 [2]教育部物质非平衡合成与调控重点实验室,西安710049

出　　处：《原子核物理评论》2020年第3期705-712,共8页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(11875213);陕西省自然科学基础研究计划项目(2019JM-050)。

摘　　要：在PNJL模型下研究了临界点和旋节线边界上的临界指数。计算表明四个标准的临界指数α,β,γ,δ在平均场近似下与朗道-金斯堡理论的预言一致。重子数涨落分布峰态的临界指数η(≈2)大于偏态的临界指数ζ(≈1),这表明,如果在重离子碰撞实验中可以达到临界区域,峰态的测量比偏态的测量更加敏感。计算结果还表明,偏态(峰态)在旋节线边界上的临界指数与在临界点的临界指数具有相同的发散强度。根据重子数在不稳定相和亚稳相的剧烈涨落及峰态和偏态在旋节线边界上发散的特点,在将来的实验中用于鉴别一阶相变的信号在一定程度上会被干扰,一些偏离标准一阶相变的信号或许会在观测中发现。The critical exponents at the Critical end Point(CEP)and the spinodal boundaries are investigated in the Poyakov-Nambu--Jona-Lasinio(PNJL)model.The numerical results show that the four standard critical exponents,α,β,γandδ,are consistent with Landau-Ginzburg theory in the mean-field approximation.The critical exponentη(≈2)correlated to kurtosis is larger than the critical exponentζ(≈1)of skewness at the CEP,which indicates that the measurement of kurtosis is more sensitive than skewness if the critical region can be reached in heavy-ion collision.The calculation also shows that the critical exponent of skewness~(kurtosis)along the spinodal line has the same divergent strength as that at the CEP.Due to the violent fluctuations in the unstable and metastable phases and the divergence of skewness and kurtosis at the spinodal boundaries,the signals to identify the first-order transition in the future experiments will be disturbed to a certain degree.Some deviations from the prediction of standard first-order transition may be found in observation.

关 键 词：临界指数 重子数涨落 旋节线不稳定 一阶相变 非平衡效应 

分 类 号：O571.6[理学—粒子物理与原子核物理]