Semileptonic decays of heavy {lambda} baryons in a quark model
- Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States)
- Department of Physics, Old Dominion University, Norfolk, Virginia 23529 (United States)
The semileptonic decays of {lambda}{sub c} and {lambda}{sub b} are treated in the framework of a constituent quark model. Both nonrelativistic and semirelativistic Hamiltonians are used to obtain the baryon wave functions from a fit to the spectra, and the wave functions are expanded in both the harmonic-oscillator and the Sturmian bases. The latter basis leads to form factors in which the kinematic dependence on q{sup 2} is in the form of multipoles, and the resulting form factors fall faster as a function of q{sup 2} in the available kinematic ranges. As a result, decay rates obtained in the two models with the Sturmian basis are significantly smaller than those obtained with the harmonic-oscillator basis. In the case of the {lambda}{sub c}, decay rates calculated with the Sturmian basis are closer to the experimentally reported rates. However, we find a semileptonic branching fraction for the {lambda}{sub c} to decay to excited {lambda}{sup *} states of 11 to 19%, in contradiction to what is assumed in available experimental analyses. Our prediction for the {lambda}{sub b} semileptonic decays is that decays to the ground state {lambda}{sub c} provide a little less than 70% of the total semileptonic decay rate. For the decays {lambda}{sub b}{yields}{lambda}{sub c}, the analytic form factors we obtain satisfy the relations expected from heavy-quark effective theory at the nonrecoil point, at leading and next-to-leading orders in the heavy-quark expansion. In addition, some features of the heavy-quark limit are shown to naturally persist as the mass of the heavy quark in the daughter baryon is decreased.
- OSTI ID:
- 20699004
- Journal Information:
- Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 3 Vol. 72; ISSN 0556-2813; ISSN PRVCAN
- Country of Publication:
- United States
- Language:
- English
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