Taste symmetry breaking with HYP-smeared staggered fermions

Abstract

We study the impact of hypercubic (HYP) smearing on the size of taste breaking for staggered fermions, comparing to unimproved and to asqtad-improved staggered fermions. As in previous studies, we find a substantial reduction in taste-breaking compared to unimproved staggered fermions (by a factor of 4-7 on lattices with spacing $a\approx 0.1$fm). In addition, we observe that discretization effects of next-to-leading order in the chiral expansion ($\mathcal{O}(a^2{p}^2)$) are markedly reduced by HYP smearing. Compared to asqtad valence fermions, we find that taste-breaking in the pion spectrum is reduced by a factor of 2.5-3, down to a level comparable to the expected size of generic $\mathcal{O}(a^2)$ effects. Our results suggest that, once one reaches a lattice spacing of $a\approx 0.09$fm, taste-breaking will be small enough after HYP smearing that one can use a modified power counting in which $\mathcal{O}(a^2)\ll \mathcal{O}(p^2)$, simplify fitting to phenomenologically interesting quantities.

14 pages, 13 figures, references updated, minor changes

References in corpus (1)

• Flavor symmetry breaking and scaling for improved staggered actions in quenched QCD