Hadronic weak decays of A < inf > b < /inf > baryon in the covariant oscillator quark model

Abstract

Cabibbo allowed two-body hadronic weak decays of Λb baryons are analyzed in the factorization approximation. We use the covariant oscillator quark model to evaluate the heavy → heavy and heavy → light form factors. When applied in the heavy quark limit, our form factors satisfy all the constraints imposed by heavy quark symmetry. The decay rates and up-down asymmetries for Λb baryon decaying into Λc + P(V) are calculated. It is found that the up-down asymmetry is negative in all these decay modes. Furthermore, the prediction Br(Λb → Λ + J/ψ) = 2.49 × 10-4 is consistent with the recent experimental data. Finally it is pointed out that the CKM-Wolfenstein parameter ρ2 + η2, where η is the CP phase, can be determined from the ratio of the widths Λb → ΛD̄0 and Λb → ΛJ/ψ, independent of the QCD parameter. The value of (ρ2 + η2)1/2 calculated in our model agrees very well with the value recently predicted by Rosner.