Abstract

Using the covariant constituent quark model previously developed by us, we calculate the differential rate and the forward-backward asymmetries on the lepton and hadron side for the rare baryon decays Lambda(b) -> Lambda l(+)l(-) (l = e, mu, tau) and Lambda(b) -> Lambda gamma. We use helicity methods to write down a threefold joint angular decay distribution for the cascade decay Lambda(b) -> Lambda(-> p pi(-)) + J(eff)(-> l(+)l(-)). Through appropriate angular integrations, we obtain expressions for the rates, the lepton-side forward-backward asymmetry, and the polarization of the daughter baryon Lambda leading to a hadron-side forward-backward asymmetry. We present numerical results on these observables using the covariant quark model and compare our results to the results of other calculations that have appeared in the literature. DOI: 10.1103/PhysRevD.87.074031