Calculation of $\bar B \rightarrow D^\ast \ell \bar \nu$ form factor at zero recoil using the Oktay-Kronfeld action

TL;DR

This paper reports preliminary lattice QCD calculations of the $ar B ightarrow D^ ext{*} \, \ell \, \bar \nu$ decay form factor at zero recoil, employing the Oktay-Kronfeld action for heavy quarks and HISQ for light quarks.

Contribution

First lattice QCD calculation of the $ar B \rightarrow D^* \ell \bar \nu$ form factor at zero recoil using the Oktay-Kronfeld action for heavy quarks.

Findings

Preliminary results for the form factor at zero recoil.

Use of Oktay-Kronfeld action for improved heavy quark treatment.

Application of MILC HISQ configurations for light quarks.

Abstract

We present the first preliminary results for the semileptonic form factor $h_{A_1}(w=1)/\rho_{A_j}$ at zero recoil for the $\bar B \rightarrow D^\ast \ell \bar \nu$ decay using lattice QCD with four flavors of sea quarks. We use the HISQ staggered action for the light valence and sea quarks (the MILC HISQ configurations), and the Oktay-Kronfeld (OK) action for the heavy valence quarks.