Non-perturbative renormalisation and improvement of the local vector current for quenched and unquenched Wilson fermions

TL;DR

This paper determines the renormalisation constant and improvement coefficient of the local vector current for Wilson fermions, using charge conservation, in both quenched and unquenched lattice QCD simulations.

Contribution

It provides a non-perturbative calculation of the vector current renormalisation and improvement coefficients for Wilson fermions, including unquenched cases, enhancing accuracy in lattice QCD.

Findings

Renormalisation constant matches known results for quenched fermions.

Improvement coefficients are computed for unquenched Wilson fermions.

Comparison between unimproved and improved cases highlights the effectiveness of the method.

Abstract

By considering the local vector current between nucleon states and imposing charge conservation, we determine its renormalisation constant and quark mass improvement coefficient for Symanzik $O(a)$ improved Wilson fermions. The computation is first performed for quenched fermions (and for completeness also with unimproved fermions) and compared against known results. The two-flavour unquenched case is then considered.