The \boldmath$B\to D^\ast\ell\nu$ semileptonic decay at nonzero recoil and its implications for $\ |V_{cb}\ |$ and $R(D^\ast)$

TL;DR

This paper analyzes the form factors of the $B o D^ ext{*}\ell u$ decay at nonzero recoil using lattice QCD, providing results that influence the determination of $|V_{cb}|$ and $R(D^ ext{*})$.

Contribution

The study presents nearly final lattice QCD results for $B o D^ ext{*}\ell u$ form factors at nonzero recoil, including multiple ensembles and quark actions, improving precision for CKM and decay ratio calculations.

Findings

Results will refine $|V_{cb}|$ determination.

Results impact $R(D^ ext{*})$ predictions.

Provides detailed lattice QCD form factors.

Abstract

We present nearly final results from our analysis of the form factors for $B\to D^\ast\ell\nu$ decay at nonzero recoil. Our analysis includes 15 MILC asqtad ensembles with $N_f=2+1$ flavors of sea quarks and lattice spacings ranging from $a\approx0.15$ fm down to $0.045$ fm. The valence light quarks employ the asqtad action, whereas the $b$ and $c$ quarks are treated using the Fermilab action. We discuss the impact that our results will have on $\ |V_{cb}\ |$ and $R(D^\ast)$.