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

Abstract

We report updates to an ongoing lattice-QCD calculation of the form factors for the semileptonic decays B → π`ν, Bs → K`ν, B → π`+`−, and B → K`+`−. The tree-level decays B(s) → π(K)`ν enable precise determinations of the CKM matrix element |Vub|, while the flavor-changing neutral-current interactions B → π(K)`+`− are sensitive to contributions from new physics. This work uses MILC's (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 f0, f+, and fT, including studies of systematic errors. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).