We study the anomalous breaking of U_A(1) symmetry just above the QCD phase transition for zero and two flavors of quarks, using a staggered fermion, lattice discretization. The properties of the QCD phase transition are expected to depend on the degree of U_A(1) symmetry breaking in the transition region. For the physical case of two flavors, we carry out extensive simulations on a 16^3 x 4 lattice, measuring a difference in susceptibilities which is sensitive to U_A(1) symmetry and which avoids many of the staggered fermion discretization difficulties. The results suggest that anomalous effects are at or below the 15% level.
@article{arxiv.hep-lat/9807018,
title = {Anomalous Chiral Symmetry Breaking above the QCD Phase Transition},
author = {Shailesh Chandrasekharan and Dong Chen and Norman Christ and Weonjong Lee and Robert Mawhinney and Pavlos Vranas},
journal= {arXiv preprint arXiv:hep-lat/9807018},
year = {2009}
}