Symmetry relations for heavy-to-light meson form factors at large recoil

Abstract

The description of large-recoil heavy-to-light meson form factors is reviewed in the framework of soft-collinear effective theory. At leading power in the heavy quark expansion, three classes of approximate symmetry relations arise. The relations are compared to experimental data for $D\to K^*$ and $D_s\to ϕ$ form factors, and to light-cone QCD sum rule predictions for $B\to π$ and $B\to ρ$ form factors. Implications for the extraction of $|V_{ub}|$ from semileptonic $B\to ρ$ decays are discussed.