1301.3737 (Thomas Gutsche et al.)

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    [PDF]

Thomas Gutsche, Mikhail A. Ivanov, Jurgen G. Korner, Valery E. Lyubovitskij, Pietro Santorelli

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 three-fold 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 (FB) 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.

View original: http://arxiv.org/abs/1301.3737