Lattice QCD calculation of form factors describing the rare decays B→K*ℓ+ℓ- and Bs→ϕℓ+ℓ-

The rare decays B0→K^*0μ⁺μ^- and B_s→ϕμ⁺μ^- 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^* and B_s→ϕ form factors. We also determine the form factors relevant for the decays B_s→K^*ℓν and B_s→K^¯*0ℓ⁺ℓ^-. 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.