Semileptonic B to D decays at nonzero recoil with 2+1 flavors of improved staggered quarks

TL;DR

This paper reports on progress in lattice QCD calculations of semileptonic B to D decays at nonzero recoil, aiming to improve the precision of CKM matrix element |V_cb| measurements.

Contribution

It presents methodological improvements and progress updates in lattice QCD analysis of B to D decays, enhancing the accuracy of |V_cb| extraction.

Findings

Improved analysis methods reduce statistical errors.

Enhanced parameter coverage anticipates lower final uncertainties.

Progress towards more precise |V_cb| determination.

Abstract

The Fermilab Lattice-MILC collaboration is completing a comprehensive program of heavy-light physics on the MILC (2+1)-flavor asqtad ensembles with lattice spacings as small as 0.045 fm and light-to-strange-quark mass ratios as low as 1/20. We use the Fermilab interpretation of the clover action for heavy valence quarks and the asqtad action for light valence quarks. The central goal of the program is to provide ever more exacting tests of the unitarity of the CKM matrix. We give a progress report on one part of the program, namely the analysis of the semileptonic decay B to D at both zero and nonzero recoil. Although final results are not presented, we discuss improvements in the analysis methods, the statistical errors, and the parameter coverage that we expect will lead to a significant reduction in the final error for |V_cb| from this decay channel.