The Kalman-Tran-D'Souza model and the semileptonic decay rates of heavy baryons

Abstract

We present an investigation of the inclusive semileptonic decay widths of the heavy baryons Λ Q , Σ Q and Ξ Q , ( q = b, c) performed within a relativistic constituent quark model, formulated on the light-front. In a way conceptually similar to the deep-inelastic scattering case, the H Q -baryon inclusive width is expressed as the integral of the free Q-quark partial width multiplied by a bound-state factor related to the Q-quark distribution function in the H Q . The non-perturbative meson structure is described through the quark-model wave functions, constructed via the Hamiltonian light-front formalism using as input the Kalman-Tran-D'Souza equal time wave functions. A link between spectroscopic quark models and the H Q decay physics is obtained in this way. It is shown that the bound-state effects and the Fermi motion of the b-quark remarkably reduce the decay rate with respect to the free-quark result. Our predictions for the BR(Λ c → X sl ν e ) and BR(Λ b → X cl ν e ) decays are in good agreement with existing data.