Experimental Limits on Weak Annihilation Contributions to b -->u ell nu Decay

TL;DR

This paper establishes the first experimental limits on weak annihilation contributions in charmless semileptonic B decays, which could affect the precision of |Vub| measurements, by analyzing high-q^2 decay data.

Contribution

It provides the first experimental constraints on weak annihilation effects in B decays, reducing uncertainties in |Vub| extraction methods.

Findings

Limit of (Gamma_WA/Gamma_b->u) < 7.4% at 90% CL

Assessed impact of WA on previous |Vub| determinations

Used theoretical models to interpret experimental data

Abstract

We present the first experimental limits on high-q^2 contributions to charmless semileptonic B decays of the form expected from the Weak Annihilation (WA) decay mechanism. Such contributions could bias determinations of |Vub| from inclusive measurements of B-> X_u lnu. Using a wide range of models based on available theoretical input we set a limit of (Gamma_WA/Gamma_b->u) < 7.4% (90% confidence level) on the WA fraction, and assess the impact on previous inclusive determinations of |Vub|.