SCET sum rules for Λb → Λℓ+ℓ−, Λγ decays

A bstract We construct light-cone sum rules for various types of effective form factors in the Λ b → Λ ℓ + ℓ − and Λ b → Λ γ decays by analyzing vacuum-to-Λ b (or γ * -to-Λ b ) correlation functions with the light Λ-baryon interpolating current. These form factors, defined via hadronic matrix elements within soft-collinear effective theory (SCET), enter the next-to-leading-power QCD factorization formulas for large-recoil transitions. Implementing the perturbative matching from SCET I to heavy quark effective theory, we determine the hard-collinear functions at next-to-leading-order accuracy. Based on light-cone sum rule predictions for the Λ b → Λ form factors, we compute the q 2 -dependent differential branching fraction, forward-backward asymmetry and dilepton longitudinal polarization fraction for Λ b → Λ ℓ + ℓ − decay, as well as the branching fraction for Λ b → Λ γ decay.