We discuss the role of the axial U(1)A symmetry in the chiral phase transition using the U(Nf)R×U(Nf)L linear sigma model with two massless quark flavors. We expect that above a certain temperature the axial U(1)A symmetry will be effectively restored as well as SU(Nf)R×SU(Nf)L. Then we can construct a string-like static solution the η string and a kink-like classical solution the domain wall during the chiral phase transition. We give out the possible signals for detecting the domain wall in ultrarelativistic heavy-ion collisions.
@article{arxiv.hep-ph/0405145,
title = {Domain Wall in the Linear Sigma Model},
author = {Hong Mao and Yunde Li and Tao Huang},
journal= {arXiv preprint arXiv:hep-ph/0405145},
year = {2011}
}