Form factors for semileptonic B(s) -> D*(s) l nu_l decays

TL;DR

This paper explores extracting form factors for semileptonic B(s) decays to D*(s) using lattice QCD data, aiding in CKM matrix element determination and lepton universality tests.

Contribution

It introduces a method to extract form factors for vector final states in B(s) decays using existing lattice data and the narrow width approximation.

Findings

Preliminary results for B_s → D_s^* ℓ ν_ℓ decays are presented.

Uses RBC/UKQCD lattice ensembles with domain-wall fermions.

Employs relativistic heavy quark action for bottom quarks.

Abstract

Semileptonic $B_{(s)}$ decays are of great phenomenological interest because they allow to extract CKM matrix elements or test lepton flavour universality. Taking advantage of existing data, we explore extracting form factors for vector final states using the narrow width approximation. Based on RBC/UKQCD's set of 2+1 flavour gauge field ensembles with Shamir domain-wall fermion and Iwasaki gauge field action, we study semileptonic $B_{(s)}$ decays using domain-wall fermions for light, strange and charm quarks, whereas bottom quarks are simulated with the relativistic heavy quark (RHQ) action. Exploratory results for $B_s \to D_s^* \ell \nu_\ell$ are presented.