Improvement of the pion spectrum with HYP-smeared staggered fermions

We extend our previous study of taste-symmetry breaking using HYP-smeared staggered fermions in two ways. First, we improve the statistics of a comparison of unimproved and HYP-smeared staggered fermions on quenched lattices with a � 0.1 fm. This allows us to obtain a signal for all pion tastes, rather than just a subset, and thus to make a c omplete comparison. In addition, it allows us to differentiate between wall and local sources . Second, we compare HYP-smeared valence quarks to asqtad valence quarks on 2+1 flavor unquenc hed MILC lattices. We find that taste breaking is substantially reduced by HYP-smearing, bringing the size of this discretization effect (which is the dominant such effect with staggered fermions) down to the size expected generically for any fermion type.