Reweighting of the form factors in exclusive B --> X ell nu decays

TL;DR

This paper introduces a reweighting technique and software tool for comparing form factor models in exclusive B to X l nu decays, enhancing the precision of |Vub| measurements.

Contribution

It develops a flexible reweighting method and software that can be used with any event generator to improve form factor model comparisons in B decays.

Findings

Validated the software with ISGW2 form factor hypothesis.

Demonstrated the tool's potential to reduce errors in |Vub| measurements.

Enabled easy implementation of various form factor models.

Abstract

A form factor reweighting technique has been elaborated to permit relatively easy comparisons between different form factor models applied to exclusive B --> X l nu decays. The software tool developped for this purpose is described. It can be used with any event generator, three of which were used in this work: ISGW2, PHSP and FLATQ2, a new powerful generator. The software tool allows an easy and reliable implementation of any form factor model. The tool has been fully validated with the ISGW2 form factor hypothesis. The results of our present studies indicate that the combined use of the FLATQ2 generator and the form factor reweighting tool should play a very important role in future exclusive |Vub| measurements, with largely reduced errors.