Non-perturbative effects in [formula omitted] for large dilepton invariant mass

Abstract

We reconsider the calculation of ϕ( Λ QCD 2/ m b 2) non-perturbative corrections to B→ X Sl +l − decay. Our analysis confirms the results of Ali et al. for the dilepton invariant mass spectrum, which were in disagreement with an earlier publication, and for the lepton forward-backward asymmetry. We also give expressions for the ϕ( Λ QCD 2/ m b 2) corrections to the left-right asymmetry. In addition we discuss the breakdown of the heavy quark expansion near the point of maximal dilepton invariant mass q 2 and consider a model-independent approach to this region using heavy hadron chiral perturbation theory. The modes B → Kl +l − and B → Kπl +l − , which determine the endpoint region of the inclusive decay, are analyzed within this framework. An interpolation is suggested between the region of moderately high q 2, where the heavy quark expansion is still valid, and the vicinity of the endpoint described by chiral perturbation theory. We also comment on further non-perturbative effects in B→ X Sl +l − .