Semileptonic Decays of Heavy Omega Baryons in a Quark Model

The semileptonic decays of (Omega)c and (Omega)b are treated in the framework of a constituent quark model developed in a previous paper on the semileptonic decays of heavy Λ baryons. Analytic results for the form factors for the decays to ground states and a number of excited states are evaluated. For (Omega)b to (Omega)c the form factors obtained are shown to satisfy the relations predicted at leading order in the heavy-quark effective theory at the non-recoil point. A modified fit of nonrelativistic and semirelativistic Hamiltonians generates configuration-mixed baryon wave functions from the known masses and the measured Λc+ → Λe+ν rate, with wave functions expanded in both harmonic oscillator and Sturmian bases. Decay rates of (Omega)b to pairs of ground and excited (Omega)c states related by heavy-quark symmetry calculated using these configuration-mixed wave functions are in the ratios expected from heavy-quark effective theory, to a good approximation. Our predictions for the semileptonic elastic branching fraction of (Omega)Q vary minimally within the models we use. We obtain an average value of (84 ± 2%) for the fraction of (Omega)c → Ξ(*) decays to ground states, and 91% for the fraction of (Omega)c → (Omega)(*) decays to the ground state (Omega). The elastic fraction of (Omega)b → (Omega)c ranges from about 50% calculated with the two harmonic-oscillator models, to about 67% calculated with the two Sturmian models