磁场背景下有限温度NJL模型的手征性质  

The chiral properties of the NJL model in a magnetic background at finite temperature

作　　者：陈建兴[1] 陈圆圆 王丽[1] 候金鑫 CHEN Jianxing,CHEN Yuanyuan,WANG Li,HOU Jinxin(School of Physics and Electronic Technology,Liaoning Normal University, Dalian 116029, Chin)

机构地区：[1]辽宁师范大学物理与电子技术学院,辽宁大连116029

出　　处：《辽宁师范大学学报（自然科学版）》2018年第2期35-42,共8页Journal of Liaoning Normal University:Natural Science Edition

摘　　要：研究有限温度时均匀磁场背景下NJL模型的手征性质,计算不同磁场强度时有限温度和化学势下的手征凝聚和相图.利用玻色子化方法,得到具有辅助玻色子场的NJL模型拉格朗日密度,以此研究超出平均场近似的情形.通过使用最优化微扰论(OPT)方法,在微扰展开到一阶时,计入了部分高阶效应.计算结果表明,相变的性质与该模型在平均场近似下定性一致.相变线上存在两种不同类型的相变:在高温低化学势下是平滑的过渡,在低温高化学势下是一阶相变,相变存在临界终点(CEP).磁场增强会加剧手征对称性破缺,具有磁催化作用.随着磁场增强,CEP向相图的左上方移动,即对应的临界温度升高而临界化学势降低.The chiral properties of the NJL model in a uniform magnetic background at finite temperature are investigated and chiral condensation and phase diagrams at finite temperature and chemical potential are obtained with different strength of the magnetic field.The Bosonized NJL Lagrangian with auxiliary boson fields is obtained and through which the situation beyond the mean field approximation is investigated.By using the OPT method,higher order effects are partly included in the first order perturbative expansion.The results show that the qualitative properties of the phase transition are consistent with those of NJL models in the mean field approximation.On the phase boundary two types of phase transitions exist：a smooth crossover at high temperature and low chemical potential,a first order phase transition at low temperature and high chemical potential.Critical end point（CEP）exits.Magnetic field intensifies the chiral symmetry breaking and magnetic catalysis happens.With increasing strength of the magnetic field,the CEPs shift to the upper left of the phase diagram,in other words,the correspording critical temperature increases and the critical chemical potential decreases.

关 键 词：NJL模型 磁场背景 手征相变 OPT方法 超出平均场近似 

分 类 号：O572.33[理学—粒子物理与原子核物理]