Evidence for eta prime - pion splitting in unquenched lattice QCD

Abstract

We perform an extrapolation from negative to positive flavour numbers of full QCD lattice estimates of the $\hat{I}{\cdot }^{\prime }$ mass. The extrapolations are carried out by keeping $\ddot{I}$ and $\ddot{I}€$ masses at fixed values. We find an $\hat{I}{\cdot }^{\prime }$ -- $\ddot{I}€$ splitting which shows a flavour dependence consistent with the Witten Veneziano formula based on the $U(1)$ anomaly. The quantitative splitting is consistent with the estimates made in the quenched approximation.

22 pages, uuencoded latex files, text + 8 figures