Imprints of CP-violation asymmetries in rare b ' †'.," + '.," ' ' decay in a family non-universal Z ' €2 model

Abstract

We investigate the exclusive rare baryonic $\Lambda -{b} \to \Lambda \ell {+ }\ell {-}$ decay in a family non-universal $Z{\prime }$ model, which is one of the natural extensions of the Standard Model. Using transition form factors, calculated in the framework of light-cone QCD sum rules, we analyze the effects of polarized and unpolarized CP-violation asymmetries on the above-mentioned semileptonic decays of the $\Lambda -b$ baryon. Our results indicate that the values of unpolarized and polarized CP-violation asymmetries are considerable in both the $\Lambda -{b} \to \Lambda \mu {+ }\mu {-}$ and $\Lambda -{b} \to \Lambda \tau {+ }\tau {-}$ channels, and hence they give a clear indication of new physics arising from the neutral $Z{\prime }$ gauge boson. It is hoped that the measurements of these CP-violating asymmetries will not only help us to find hints of new physics, but also provide a tool to determine the precise values of the parameters of the $Z{\prime }$ gauge boson.