Out-of-equilibrium UA(1) symmetry breaking in electromagnetic fields
Out-of-equilibrium UA(1) symmetry breaking in electromagnetic fields
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DOI：
10.1103/physrevd.98.016007
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发表时间：
2017-11
影响因子：
5
通讯作者：
Xingyu Guo;P. Zhuang
中科院分区：
文献类型：
--
作者：
Xingyu Guo;P. Zhuang
在等时Wigner函数框架下，系统地研究了外电磁场作用下手征对称性破缺和U_A（1）$对称性破缺的量子效应。本文导出了Nambu-Jona-Lasinio模型中夸克分布函数、手征凝聚和π介子凝聚的输运方程和约束方程。通过对方程进行半经典展开，手征对称性在经典水平上破缺，而U_A（1）$对称性破缺仅发生在量子水平上。在准粒子近似下，夸克离壳效应导致手征凝聚和π凝聚的强振荡。
We systematically study quantum effect on chiral and $U_A(1)$ symmetry breaking under external electromagnetic fields in the frame of equal-time Wigner function formalism. We derive the transport and constraint equations for the quark distribution functions and the chiral and pion condensates in a Nambu--Jona-Lasinio model. By taking semi-classical expansion of the equations, chiral symmetry is broken at classical level, while $U_A(1)$ symmetry breaking happens only at quantum level. Beyond quasi-particle approximation, the quark off-shell effect leads to strong oscillation for the chiral and pion condensates.