Lepton Asymmetries in Heavy Baryon Decays of ${\Lambda }_b\to \Lambda l^{+}{l}^{-}$

Abstract

We study the dilepton forward-backward and the longitudinal, normal and transverse lepton polarization asymmetries in the heavy baryon decays of ${\Lambda }_b\to \Lambda l^{+}{l}^{-}$. We show that the asymmetries have a less dependence on the non-perturbative QCD effects. In the standard model, we find that the integrated forward-backward asymmetries (FBAs) and three components of the polarizations in the QCD sum rule approach (pole model) are $-0.13(-0.12)$ and $(58.3,-9.4,-0.07)$ ($(58.3,-12.6,-0.07)$) for ${\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-}$ and $-0.04(-0.03)$ and $(10.9,-10.0,-0.39)$ ($(10.9,-0.2,-0.34)$) for ${\Lambda }_b\to \Lambda {\tau }^{+}{\tau }^{-}$, respectively.

Comments: 10 pages, 9 figures, revised version