$B_s\to D_s^{(\ast )}$ form factors from lattice QCD with $N_f=2$ Wilson-clover quarks

Abstract

We report on a two-flavour lattice QCD determination of the $B_s\to D_s$ and $B_s\to D_s^{\ast }$ transitions, which in the heavy quark limit can be parameterised by the form factors $\mathcal{G}$, and $h_{{\text{A}}_1}$, $h_{{\text{A}}_2}$ and $h_{{\text{A}}_3}$. In the search of New Physics through tests of lepton-flavour universality, $B_s$ decay channels are complementary to $B$ decays and widely studied at $B$ factories and LHCb. The purpose of our study is to explore a suitable method to extract form factors associated with $b\to c$ currents from lattice QCD. In particular, we present numerical results for $\mathcal{G}$ and $h_{{\text{A}}_1}$.