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

We present an investigation of the inclusive semileptonic decay widths of t he heavy baryons Lambda (Q), Sigma (Q) and Xi (Q), (q = b, c) performed wit hin 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 p artial width multiplied by a bound-state factor related to the Q-quark dist ribution function in the H-Q. The non-perturbative mason structure is descr ibed through the quark-model wave functions, constructed via the Hamiltonia n light-front formalism using as input the Kalman-Tran-D'Souza equal time w ave 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 a nd the Fermi motion of the b-quark remarkably reduce the decay rate with re spect to the free-quark result. Our predictions for the BR(Lambda (c) ->X(s )lv(l)) and BR(Lambda (l) -> X(s)lv(l)) decays are in good agreement with e xisting data.