Rare baryon decays Lambda(b) -> Lambda l(+)l(-) (l = e, mu, tau) and Lambda(b) -> Lambda gamma: Differential and total rates, lepton- and hadron-side forward-backward asymmetries

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