F_B from moving B mesons

TL;DR

This paper presents lattice QCD calculations of the B meson decay constant using various momentum states and current components, emphasizing systematic error checks and optimal smearing techniques.

Contribution

It provides a comprehensive analysis of f_B calculations at different momenta and current components, highlighting the importance of smearing optimization for accuracy.

Findings

All determinations of f_B agree within errors.

Optimal smearing involves narrow b quark smearing at non-zero momentum.

Different current components yield consistent results.

Abstract

We show results for the B meson decay constant calculated both for B mesons at rest and those with non-zero momentum and using both the temporal and spatial components of the axial vector current. It is an important check of lattice systematic errors that all these determinations of f_B should agree. We also describe how well different smearings for the B meson work at non-zero momentum - the optimal smearing has a narrow smearing for the b quark.