|Vub| from Exclusive Semileptonic B--> rho Decays

TL;DR

This paper employs Omnes representations of form factors to combine experimental and theoretical data, deriving a value for |Vub| from exclusive B→rho decays that is slightly lower than other methods, highlighting discrepancies in CKM matrix element determinations.

Contribution

It introduces a novel approach using Omnes representations for form factors in B→rho decays to extract |Vub|, providing a new perspective on CKM matrix element measurements.

Findings

|Vub| = (2.8 ± 0.2) x 10^{-3} from B→rho decays

Result is slightly lower than B→pi decay extractions

Discrepancy increases with inclusive decay results

Abstract

We use Omnes representations of the form factors V, A_1 and A_2 for exclusive semileptonic B--> rho decays, and apply them to combine experimental partial branching fraction information with theoretical calculations of the three form factors to extract |Vub|. We find a slightly lower result, |Vub|=(2.8 +- 0.2)x 10^{-3}, than the values extracted from exclusive semileptonic B-->pi decays and using all other inputs in CKM fits. The disagreement is greater when we compare to the result extracted from inclusive B -> X_u l nu decays.