HQET form factors for B_s → Klv decays beyond leading order

Abstract

Abstract. We compute semi-leptonic B s decay form factors using Heavy Quark Effective Theory on the lattice. To obtain good control of the 1/m b expansion, one has to take into account not only the leading static order but also the terms arising at O (1/m b ): kinetic, spin and current insertions. We show results for these terms calculated through the ratio method, using our prior results for the static order. After combining them with nonperturbative HQET parameters they can be continuum-extrapolated to give the QCD form factor correct up to O 1/m 2 b corrections and without O (α s (m b ) n ) corrections.