Proper time regularization and the QCD chiral phase transition

Zhu-Fang Cui,Hong-Shi Zong,Jin-Li Zhang

doi:10.1038/srep45937

Zhu-Fang Cui, Hong-Shi Zong + Show 1 more

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https://doi.org/10.1038/srep45937

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Abstract

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.

Highlights

We study the Quantum ChromoDynamics (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
If we take into account the influence of quark condensate to the coupling strength, it is found that a critical end point (CEP) may appear
For the QCD phase diagram beyond the chiral limit, a popular scenario is a crossover at finite T and low μ, which turns into first order for larger μ at a possible critical end point (CEP)

Summary

OPEN Proper time regularization and the QCD chiral phase transition

Zhu-Fang Cui[1,2], Jin-Li Zhang1 & Hong-Shi Zong[1,2,3] received: 10 January 2017 accepted: 06 March 2017. For the QCD phase diagram beyond the chiral limit (that is for finite quark masses), a popular scenario is a crossover at finite T and low μ, which turns into first order for larger μ at a possible critical end point (CEP). The search for such a CEP is one of the main goals in the high energy physics experiments, such as the beam energy scan (BES) program[1,2,3,4,5]. To cure the ultraviolet (UV) divergence of this model, the covariant proper-time regularization (PTR) is adopted in this work

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