Determining |V_{ub}| from the sum rule for semileptonic B decay

TL;DR

This paper presents a theoretically clean and experimentally efficient sum rule method for precisely determining |V_{ub}| from inclusive semileptonic B decays, avoiding perturbative QCD uncertainties.

Contribution

It introduces a sum rule based on light-cone expansion and quantum number conservation that eliminates perturbative QCD corrections and reduces hadronic uncertainties in measuring |V_{ub}|.

Findings

Sum rule is free of perturbative QCD corrections.

Method effectively discriminates B→X_uℓν from background.

Includes analysis of leading QCD corrections to the lepton spectrum.

Abstract

A precise determination of |V_{ub}| can be obtained exploiting the sum rule for inclusive charmless semileptonic B-meson decays. The sum rule is derived on the basis of light-cone expansion and b-flavored quantum number conservation. The sum rule does not receive any perturbative QCD correction. In this determination of |V_{ub}|, there is no perturbative QCD uncertainty, while the dominant hadronic uncertainty is avoided. Moreover, this method is not only theoretically quite clean, but experimentally also very efficient in the discrimination between B\to X_u\ell\nu signal and B\to X_c\ell\nu background. The sum rule requires measuring the lepton pair spectrum. We analyze the lepton pair spectrum, including the leading perturbative and nonperturbative QCD corrections.