Speaker
Description
We present our nonperturbative Lattice QCD calculation to determine semileptonic form factors for exclusive $B_s \to K \ell \nu$ and $B_s \to D_s \ell \nu$ decays. Our calculation is based on RBC-UKQCD's set of 2+1 dynamical flavor gauge field ensembles and in the valence sector we use domain wall fermions for up/down, strange, and charm quarks, whereas bottom quarks are simulated with the relativistic heavy quark action. The continuum limit is based on three lattice spacings and form factors over the full $q^2$ range are shown.
These form factors are the basis to predict ratios studying lepton flavor universality or, when combined with experimental results, to obtain CKM matrix elements $|V_{cb}|$ and $|V_{ub}|$. Due to different experimental and theoretical set-ups, these alternative $b$-decay channels may also help to shed light on the tension between the analysis of inclusive and exclusive decays or may further serve as proxy for corresponding $B$ decays.
