B -> D* l nu and B -> D l nu form factors in staggered chiral perturbation theory

TL;DR

This paper computes B to D(*) form factors at zero recoil using staggered chiral perturbation theory, accounting for lattice discretization errors, finite volume effects, and different sea quark mass configurations.

Contribution

It provides the first detailed calculation of B to D(*) form factors in staggered chiral perturbation theory including discretization and finite volume corrections.

Findings

Form factors calculated at zero recoil with staggered quarks.

Quantitative estimates of discretization errors and finite volume effects.

Results applicable to current lattice QCD simulations.

Abstract

We calculate the B -> D and B -> D* form factors at zero recoil in Staggered Chiral Perturbation Theory. We consider heavy-light mesons in which only the light (u, d, or s) quark is staggered; current lattice simulations generally use a highly improved action such as the Fermilab or NRQCD action for the heavy (b or c) quark. We work to lowest nontrivial order in the heavy quark expansion and to one-loop in the chiral expansion. We present results for a partially quenched theory with three sea quarks in which there are no mass degeneracies (the "1+1+1" theory) and for a partially quenched theory in which the u and d sea quark masses are equal (the "2+1" theory). We also present results for full (2+1) QCD, along with a numerical estimate of the size of staggered discretization errors. Finally, we calculate the finite volume corrections to the form factors and estimate their numerical size in current lattice simulations.