Quenched lattice calculation of the B --> D l nu decay rate

TL;DR

This paper presents a quenched lattice QCD calculation of the B to D semileptonic decay form factor, enabling more precise extraction of the CKM matrix element Vcb from experimental data.

Contribution

It introduces a novel application of the step scaling method and twisted boundary conditions to compute the decay form factor at physical quark masses and finite momentum transfer.

Findings

Form factor G(w) computed at physical quark masses

Results facilitate model-independent extraction of Vcb

Method improves accuracy of lattice QCD decay calculations

Abstract

We calculate, in the continuum limit of quenched lattice QCD, the form factor that enters in the decay rate of the semileptonic decay B --> D l nu. Making use of the step scaling method (SSM), previously introduced to handle two scale problems in lattice QCD, and of flavour twisted boundary conditions we extract G(w) at finite momentum transfer and at the physical values of the heavy quark masses. Our results can be used in order to extract the CKM matrix element Vcb by the experimental decay rate without model dependent extrapolations.