Abstract:
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.