Subleading light-cone distribution functions in the decays Λb→Xsγ and Λb→Xuℓν̄ℓ

In this Letter we investigate the subleading twist corrections to the photon energy spectrum in the decay Λb→Xsγ and to the lepton energy spectrum in Λb→Xuℓν̄ℓ. As a first step we rederive the matching coefficients of the subleading twist using a much simpler method. Parametrizing the matrix elements for Λb and using reparametrization invariance, we show that the energy spectra close to the endpoints are given in terms of only a single universal function.