Lattice QCD calculation of form factors describing the rare decays B → K[superscript *]ℓ[superscript +]ℓ[superscript -] and B[subscript s] → φℓ[superscript +]ℓ[superscript -]

Abstract

The rare decays B[superscript 0] → K[superscript *0]μ[superscript +]μ[superscript −] and B[subscript s] → ϕμ[superscript +]μ[superscript −] are now being observed with enough precision to test Standard Model predictions. A full understanding of these decays requires accurate determinations of the corresponding hadronic form factors. Here we present results of lattice QCD calculations of the B → K[superscript *] and B[subscript s] → ϕ form factors. We also determine the form factors relevant for the decays B[subscript s] → K[superscript *]ℓν and B[subscript s] → [bar over K][superscript *0]ℓ[superscript +]ℓ[superscript −]. We use full-QCD configurations including 2+1 flavors of sea quarks using an improved staggered action, and we employ lattice nonrelativistic QCD to describe the bottom quark.