Heavy-light decay constant at the 1/m order of HQET

TL;DR

This paper introduces a non-perturbative method to compute the heavy-light meson decay constant in HQET including 1/m corrections, using a stepwise volume evolution and matching with QCD.

Contribution

It develops a novel non-perturbative approach for calculating decay constants in HQET with 1/m corrections, based on small-volume matching and large-volume evolution.

Findings

Preliminary results in the quenched approximation demonstrate the method's feasibility.

The approach allows for systematic inclusion of 1/m corrections in decay constant calculations.

The method improves the precision of heavy-light meson decay constant estimates.

Abstract

Following the strategy developed by the ALPHA collaboration, we present a method to compute non-perturbatively the decay constant of a heavy-light meson in HQET including the 1/m corrections. We start by a matching between HQET and QCD in a small volume to determine the parameters of the effective theory non-perturbatively. Observables in the effective theory are then evolved to larger volumes. In two steps a large enough volume is reached to determine the physical decay constant. Some preliminary results in the quenched approximation are shown.