Semileptonic form factors D to pi, K and B to pi, K from a fine lattice

TL;DR

This paper computes semileptonic form factors for D and B meson decays using a fine lattice in the quenched approximation, reducing systematic errors and providing results consistent with other methods.

Contribution

It presents a relativistic lattice calculation of D and B meson semileptonic form factors near the physical B mass with minimized extrapolation errors.

Findings

Form factors at q^2=0 for D and B decays are provided.

Results agree well with other lattice and sum rule calculations.

Systematic errors are reduced due to fine lattice spacing.

Abstract

We extract the form factors relevant for semileptonic decays of D and B mesons from a relativistic computation on a fine lattice in the quenched approximation. The lattice spacing is a=0.04 fm (corresponding to a^{-1}=4.97 GeV), which allows us to run very close to the physical B meson mass, and to reduce the systematic errors associated with the extrapolation in terms of a heavy quark expansion. For decays of D and D_s mesons, our results for the physical form factors at q^2=0 are as follows: f_+^{D to pi}(0)= 0.74(6)(4), f_+^{D to K}(0)= 0.78(5)(4) and f_+^{D_s to K}(0)=0.68(4)(3). Similarly, for B and B_s we find: f_+^{B to pi}(0)=0.27(7)(5), f_+^{B to K}(0)=0.32(6)(6) and f_+^{B_s to K}(0)=0.23(5)(4). We compare our results with other quenched and unquenched lattice calculations, as well as with light-cone sum rule predictions, finding good agreement.