Hadronic Weak Decays of b Baryon in the Covariant Oscillator Quark Model

Cabibbo allowed two-body hadronic weak decays of Lambda b baryons areanalyzed in the factorization approximation. We use the covariant oscillatorquark model to evaluate the heavy to heavy and heavy to light form factors.When applied in the heavy quark limit, our form factors satisfy all theconstraints imposed by heavy quark symmetry. The decay rates and up-downasymmetries for Lambda b baryon decaying into Lambda c +P(V) are calculated. Itis found that the up-down asymmetry is negative in all these decay modes.Furthermore, the prediction Br(Lambda b to Lambda+J/psi)=2.49 times 10^-4 isconsistent with the recent experimental data. Finally it is pointed out thatthe CKM-Wolfenstein parameter rho^2+eta^2, where eta is the CP phase, can bedetermined from the ratio of the widths Lambda b to Lambda bar D^0 and Lambda bto Lambda J/psi, independent of the QCD parameter. The value of (rho^2+eta^2)^1/2 calculated in our model agrees very well with the value recentlypredicted by Rosner.Comment: 10 pages, uses ptptex.st