Non-perturbative Renormalization of Improved Staggered Bilinears

TL;DR

This paper computes non-perturbative renormalization factors for staggered bilinears on fine lattice ensembles, comparing with perturbation theory, and explores RI/SMOM schemes for improved accuracy in weak matrix element calculations.

Contribution

It extends previous NPR work to finer lattices, compares non-perturbative and perturbative Z-factors, and implements RI/SMOM conditions for staggered fermions.

Findings

Agreement between NPR and perturbation theory at fine lattice spacing

First results for RI/SMOM renormalization conditions with staggered fermions

Establishment of a methodology for non-perturbative matching in weak matrix element computations

Abstract

We compute Z-factors for general staggered bilinears on fine (a \approx 0.09 fm) MILC ensembles using both asqtad and HYP-smeared valence actions, comparing the results to the predictions of one-loop perturbation theory. This is an extension of previous work on the coarse (a \approx 0.12 fm) MILC ensembles. It provides a laboratory for studying NPR methodology in the staggered context, and is an important stepping stone for fully non-perturbative matching factors in ongoing computations of B_K and other weak matrix elements. We also implement non-exceptional RI/SMOM renormalization conditions using the asqtad action and present first results.