We determine the CKM parameter $|V_{ub}|$ from the exclusive semileptonic decays $B\to\pi\ell\nu_{\ell}$ and $B_{s}\to K\ell\nu_{\ell}$, employing Lattice QCD theoretical information on the form factors in combination with experimental measurements of the differential branching ratio distributions.
Using Pad\'{e} approximants to the participating form factors we obtain $|V_{ub}|=3.86(11)\times10^{-3}$ and $|V_{ub}|=3.58(9)\times10^{-3}$ from the analyses of the individual decay channels, respectively, and $|V_{ub}|=3.68(5)\times10^{-3}$ from a simultaneous analysis of both decays.
Our results highlight the importance of the decay $B_{s}\to K\mu\nu_{\mu}$ in complementing the traditional $B\to\pi\ell\nu_{\ell}$ one in the exclusive determination of $|V_{ub}|$, and strengthens the case for precise measurements of the differential $B_{s}\to K\ell\nu_{\ell}$ decay rate with a finer resolution of the $q^{2}$ bins, as it would definitely allow achieving more conclusive results for $|V_{ub}|$.