6533b824fe1ef96bd127fed1

RESEARCH PRODUCT

Rare baryon decaysΛb→Λℓ+ℓ−(ℓ=e,μ,τ) andΛb→Λγ: Differential and total rates, lepton- and hadron-side forward-backward asymmetries

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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 ${\ensuremath{\Lambda}}_{b}\ensuremath{\rightarrow}\ensuremath{\Lambda}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ ($\ensuremath{\ell}=e$, $\ensuremath{\mu}$, $\ensuremath{\tau}$) and ${\ensuremath{\Lambda}}_{b}\ensuremath{\rightarrow}\ensuremath{\Lambda}\ensuremath{\gamma}$. We use helicity methods to write down a threefold joint angular decay distribution for the cascade decay ${\ensuremath{\Lambda}}_{b}\ensuremath{\rightarrow}\ensuremath{\Lambda}(\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{\ensuremath{-}})+{J}_{\mathrm{eff}}(\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}})$. Through appropriate angular integrations, we obtain expressions for the rates, the lepton-side forward-backward asymmetry, and the polarization of the daughter baryon $\ensuremath{\Lambda}$ 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.