Department of Physics, Nanjing University, Nanjing, 210093, China.
State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, CAS, Beijing, 100190, China.
Sci Rep. 2017 Apr 12;7:45937. doi: 10.1038/srep45937.
We study the QCD chiral phase transition at finite temperature and finite quark chemical potential within the two flavor Nambu-Jona-Lasinio (NJL) model, where a generalization of the proper-time regularization scheme is motivated and implemented. We find that in the chiral limit the whole transition line in the phase diagram is of second order, whereas for finite quark masses a crossover is observed. Moreover, if we take into account the influence of quark condensate to the coupling strength (which also provides a possible way of how the effective coupling varies with temperature and quark chemical potential), it is found that a CEP may appear. These findings differ substantially from other NJL results which use alternative regularization schemes, some explanation and discussion are given at the end. This indicates that the regularization scheme can have a dramatic impact on the study of the QCD phase transition within the NJL model.
我们在两味 Nambu-Jona-Lasinio（NJL）模型中研究了有限温度和有限夸克化学势下的 QCD 手征相变，其中提出并实现了一种正则化方案的推广。我们发现，在手征极限下，相图中的整个相变线是二阶的，而对于有限的夸克质量，观察到的是交叉。此外，如果我们考虑到夸克凝聚对耦合强度的影响（这也提供了有效耦合如何随温度和夸克化学势变化的一种可能方式），则可能会出现 CEP。这些发现与使用其他正则化方案的其他 NJL 结果有很大不同，最后给出了一些解释和讨论。这表明正则化方案在手征相变的 NJL 模型研究中可能会产生重大影响。
