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

Abstract

Cabibbo allowed two-body hadronic weak decays of Λ b 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 Λ b baryon decaying into Λ c + P (V ) are calculated. It is found that the up-down asymmetry is negative in all these decay modes. Furthermore, the prediction Br(Λ b → Λ + J/ψ) = 2.49 × 10 −4 is consistent with the recent experimental data. Finally it is pointed out that the CKM-Wolfenstein parameter ρ 2 + η 2 , where η is the CP phase, can be determined from the ratio of the widths Λ b → ΛD 0 and Λ b → ΛJ/ψ, independent of the QCD parameter. The value of (ρ 2 + η 2 ) 1/2 calculated in our model agrees very well with the value recently predicted by Rosner. by guest on March 23, 2015 http://ptp.oxfordjournals.org/ Downloaded from

Polarization effects in the cascade decayΛb→Λ(→pπ−)+J/ψ<

“…e þ e À ; þ À Þ for which one can safely use the zero lepton mass approximation (see Table II). Our results are presented in Tables V, VI, and VII where we compare them with the available data [1,11] and predictions of other theoretical approaches [3][4][5][6][7][8][9][10]. In Table V we present our result on the branching fraction Bðà b !…”

“…There have been a number of theoretical quark model calculations for the decay à b ! à þ J=c that are based on the factorization hypothesis [3][4][5][6][7][8][9][10]. The results of some of these calculations have been compared to the new experimental results by the LHCb Collaboration.…”

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“…F i ðΩ 0 ÞTðΩ 0 ; ΩÞF j ðΩÞdΩ 0 dΩ; (8) where Ω stands for the true decay angles and Ω 0 for the measured ones. The acceptance, efficiency, and resolution of the detector are represented by TðΩ 0 ; ΩÞ.…”

“…Various quark models are used to calculate the form factors in the factorization approximation (FA) [6][7][8][9][10] and the predictions of α b generally lie in the range from −0.2 to −0.1. In…”

Heavy baryons as polarimeters at colliders

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