Comparing B -> X_u l nu_l to B -> X_s gamma

TL;DR

This paper proposes a method to determine the ratio of CKM matrix elements V_ub and V_ts by comparing specific spectra from B meson decays, accounting for non-perturbative and radiative effects.

Contribution

It introduces a novel approach using spectral ratios of B decays to cancel non-perturbative effects and includes radiative corrections for precise CKM element extraction.

Findings

The spectral ratio cancels non-perturbative contributions at tree level.

Radiative corrections to order alpha_s are incorporated.

The method provides a cleaner determination of V_ub / V_ts.

Abstract

We suggest a method to determine V_ub / V_ts through a comparison of B -> X_u l nu_l and B -> X_s gamma. The relevant quantity is the spectrum of the light-cone component of the final state hadronic momentum, which in B -> X_s gamma is the photon energy while in B -> X_u l nu_l this requires a measurement of both hadronic energy and hadronic invariant mass. The non-perturbative contributions at tree level to these distributions are identical and may be cancelled by taking the ratio of the spectra. Radiative corrections to this comparison are discussed to order alpha_s and are combined with the non-perturbative contributions.