Manifestations of the axial anomaly in finite temperature QCD
  We compute the flavor singlet meson correlators and screening masses in quenched and $N_f=2$ QCD at $N_t=8$. The consequences of our results for the realization of the $U_A(1)$ symmetry at finite T are discussed and an interpretation of our measurements in terms of the behaviour of the low lying fermionic modes is proposed. 
J.B.Kogut, J.-F.Lagae, D.K. Sinclair