Speaker
Description
Determinations of the CKM matrix elements $|V_{ub}|$ and $|V_{cb}|$ or predictions for $R$-ratios testing lepton flavor universality can be obtained from form factors describing exclusive semileptonic $B_{(s)}$ decays. Using the framework of lattice quantum chromodynamics, we report on our form factor calculations for $B_s\to D_s \ell\nu$, $B_s\to K \ell\nu$, and $B\to \pi\ell \nu$ decays. First scalar and vector form factors with full error budget are presented for the range of momentum transfer directly accessible in our simulations. Next we show $z$-parameterization fits to extend $q^2$ over the kinematically allowed range and use the results to extract CKM matrix elements or predict $R$-ratios.
Our calculations are based on RBC-UKQCD's set of 2+1 flavor domain wall Iwasaki gauge field configurations featuring three lattice spacings of $a^{-1}$ = 1.78, 2.38, and 2.78 GeV. We simulate up/down, strange, and charm quarks using domain-wall fermions and use the relativistic heavy quark action for the bottom quarks.
| First author | Oliver Witzel |
|---|---|
| oliver.witzel@uni-siegen.de | |
| Collaboration / Activity | RBC-UKQCD |
