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

TL;DR

This paper calculates the second order direct CP asymmetry in inclusive semileptonic B_(s) decays within the Standard Model and explores potential enhancements in left-right symmetric models, finding effects are negligible in current experiments.

Contribution

It provides the first calculation of second order weak interaction CP asymmetry in B_(s) decays and estimates its maximal possible value in extended models.

Findings

Standard Model asymmetry is approximately -3.2 x 10^{-9}.

Left-right symmetric models could produce asymmetries two orders of magnitude larger.

Effects on wrong-sign lepton asymmetries in B decays are negligible.

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.