Second order direct CP asymmetry in B_(s) -> X l nu

Abstract

A direct CP asymmetry in inclusive semileptonic B_(s) decays vanishes by CPT to lowest order in weak interactions. Calculating the asymmetry at second order weak interactions in the Cabibbo-Kobayashi-Maskawa framework we find A_{sl} = (-3.2 \pm 0.9) x 10^{-9}. A maximal asymmetry which is two orders of magnitude larger is estimated in a left-right symmetric model. This quite generic upper bound implies negligible effects on wrong-sign lepton asymmetries in B^0 and B_s decays.