Semileptonic decays of heavy Ω baryons in a quark model

The semileptonic decays of Ωc and Ωb are treated in the framework of a constituent quark model developed in a previous article 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 Ωb to Ωc the form factors obtained are shown to satisfy the relations predicted at leading order in the heavy-quark effective theory at the nonrecoil 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 Ωb to pairs of ground and excited Ωc 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 ΩQ vary minimally within the models we use. We obtain an average value of (84±2%) for the fraction of Ωc→Ξ(*) decays to ground states and 91% for the fraction of Ωc→Ω(*) decays to the ground state Ω. The elastic fraction of Ωb→Ωc ranges from about 50% calculated with the two harmonic-oscillator models to about 67% calculated with the two Sturmian models