Abstract
The exclusive semileptonic decay is a key process for the determination of the Cabibbo-Kobayashi-Maskawa matrix element from the comparison of experimental rates as a function of with theoretically determined form factors. The sensitivity of the form factors to the quark mass has meant significant systematic uncertainties in lattice QCD calculations at unphysically heavy pion masses. Here, we give the first lattice QCD calculations of this process for quark masses going down to their physical values, calculating the form factor at zero recoil to 3%. We are able to resolve a long-standing controversy by showing that the soft-pion theorem result does hold as . We use the highly improved staggered quark formalism for the light quarks and show that staggered chiral perturbation theory for the dependence is almost identical to continuum chiral perturbation theory for , , and . We also give results for other processes such as .
1 More- Received 28 October 2015
DOI:https://doi.org/10.1103/PhysRevD.93.034502
This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society