Measurement of the CKM Matrix Element |Vub| with B->rho e nu Decays

TL;DR

This paper measures the branching fraction of B->rho e nu decays and extracts |Vub|, providing key insights into the quark-mixing matrix with results based on a large data sample and multiple form factor models.

Contribution

It presents the first measurement of |Vub| from B->rho e nu decays using five different form factor calculations, improving precision and understanding of this CKM matrix element.

Findings

Branching fraction Br(B0->rho- e+ nu) = (3.29 +-0.42 +-0.47 +-0.60) x 10^-4

|Vub| = (3.64 +-0.22 +-0.25 +0.39-0.56) x 10^-3

Results are consistent across different form factor models.

Abstract

We present a measurement of the branching fraction for the rare decays B->rho e nu and extract a value for the magnitude of Vub, one of the smallest elements of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix. The results are given for five different calculations of form factors used to parametrize the hadronic current in semileptonic decays. Using a sample of 55 million BBbar meson pairs recorded with the BABAR detector at the PEP-II e+e- storage ring, we obtain Br(B0->rho- e+ nu)=(3.29 +-0.42 +-0.47 +-0.60) x 10^-4 and |Vub|=(3.64 +-0.22 +-0.25 +0.39-0.56)x10^-3, where the uncertainties are statistical, systematic, and theoretical, respectively.