Lepton Asymmetries in Heavy Baryon Decays of Λb→Λl+l−\Lambda_b\to\Lambda l^+l^-

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.Comment: 10 pages, 9 figures, revised versio