We construct parametrizations of light-cone distribution amplitudes (LCDAs) for B-mesons and Λ b -baryons that obey various theoretical constraints, and which are simple to use in factorization theorems relevant for phenomenological applications in heavyflavour physics. In particular, we find the eigenfunctions of the Lange-Neubert renormalization kernel, which allow for a systematic implementation of renormalization-group evolution effects for both B-meson and Λ b -baryon decays. We also present a new strategy to construct LCDA models from momentum-space projectors, which can be used to implement Wandzura-Wilczek-like relations, and which allow for a comparison with theoretical approaches that go beyond the collinear limit for the light-quark momenta in energetic heavy-hadron decays.

No abstract

We present a systematic discussion of Λ b → Λ transition form factors in the framework of soft-collinear effective theory (SCET). The universal soft form factor, which enters the symmetry relations in the limit of large recoil energy, is calculated from a sum-rule analysis of a suitable SCET correlation function. The same method is applied to derive the leading corrections from hard-collinear gluon exchange at first order in the strong coupling constant. We present numerical estimates for form factors and form-factor ratios and their impact on decay observables in Λ b → Λµ + µ − decays.