Unquenching Effects on the Coefficients of the L\"uscher-Weisz Action

TL;DR

This paper investigates how including quark loops (unquenching) significantly impacts the coefficients in the L"uscher-Weisz action, potentially explaining observed scaling violations in unquenched lattice QCD studies.

Contribution

It provides the first perturbative calculation of unquenching effects on the Symanzik action coefficients within the L"uscher-Weisz framework.

Findings

Quark loops have surprisingly large effects on improvement coefficients.

Omitting quark loops may cause scaling violations in unquenched simulations.

Results suggest the importance of including unquenching effects for accurate lattice QCD modeling.

Abstract

The effects of unquenching on the perturbative improvement coefficients in the Symanzik action are computed within the framework of L\"uscher-Weisz on-shell improvement. We find that the effects of quark loops are surprisingly large, and their omission may well explain the scaling violations observed in some unquenched studies.