Next-to-leading order QCD corrections to spectator effects in lifetimes of beauty hadrons

Abstract

Theoretical predictions of beauty hadron lifetimes, based on the heavy quark expansion up to and including order 1/ m b 2, do not to reproduce the experimental measurements of the lifetime ratios τ( B +)/ τ( B d ) and τ( Λ b )/ τ( B d ). Large corrections to these predictions come from phase-space enhanced 1/ m b 3 contributions, i.e., hard spectator effects. In this paper we calculate the next-to-leading order QCD corrections to the Wilson coefficients of the local operators appearing at O(1/m b 3) . We find that these corrections improve the agreement with the experimental data. The lifetime ratio of charged to neutral B-mesons, τ( B +)/ τ( B d ), turns out to be in very good agreement with the corresponding measurement, whereas for τ( B s )/ τ( B d ) and τ( Λ b )/ τ( B d ) there is a residual difference at the 1 σ level. We discuss, however, why the theoretical predictions are less accurate in the latter cases.