$B_s \to K\ell\nu$ form factors from lattice QCD with domain-wall heavy quarks

Abstract

We report on our on-going study of the $B_s \to K\ell\nu$ decay in $N_f=2+1$ lattice QCD. We employ fully relativistic setup in which the M\"obius domain-wall action is used for all quark flavors. The lattice cutoff is $a^{-1} \sim 2.5$ GeV, where we take bottom quark masses up to $m_Q\!<\!0.7a^{-1}$ in order to control discretization errors. We present preliminary results for the relevant form factors extracted from correlator ratios by inspecting their ground state saturation.