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arXiv · 1711.02924

Out-of-equilibrium chiral and $U_A(1)$ symmetry breaking in electromagnetic fields

Xingyu Guo·Pengfei Zhuang
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Abstract

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.

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Xingyu Guo, Pengfei Zhuang. 2018-06-27. Out-of-equilibrium chiral and $U_A(1)$ symmetry breaking in electromagnetic fields. https://doi.org/10.1103/physrevd.98.016007

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