$B$-meson semileptonic form factors on (2+1+1)-flavor HISQ ensembles

We report updates to an ongoing lattice-QCD calculation of the form factors for the semileptonic decays $B to pi ell u$, $B_s to K ell u$, $B to pi ell^+ ell^-$, and $B to K ell^+ ell^-$. The tree-level decays $B_{(s)} to pi (K) ell u$ enable precise determinations of the CKM matrix element $|V_{ub}|$, while the flavor-changing neutral-current interactions $B to pi (K) ell^+ ell^-$ are sensitive to contributions from new physics. This work uses MILCs (2+1+1)-flavor HISQ ensembles at approximate lattice spacings between $0.057$ and $0.15$ fm, with physical sea-quark masses on four out of the seven ensembles. The valence sector is comprised of a clover $b$ quark (in the Fermilab interpretation) and HISQ light and $s$ quarks. We present preliminary results for the form factors $f_0$, $f_+$, and $f_T$, including studies of systematic errors.