Determination of the CKM Matrix Element |V_cb| from Semileptonic B Decays

TL;DR

This paper measures the CKM matrix element |V_cb| through semileptonic B decays using moments of energy and mass distributions, combining inclusive and exclusive decay analyses with Heavy Quark Expansions.

Contribution

It provides a comprehensive determination of |V_cb| by analyzing both inclusive and exclusive B decays using moments and form factors within the Heavy Quark Expansion framework.

Findings

Measured moments of electron energy and hadronic mass distributions.

Determined |V_cb| from inclusive decay moments and exclusive D* decays.

Extracted heavy quark parameters and form factors.

Abstract

We report studies of semileptonic decays, B --> X_c l nu, based on a sample of 88 million BB events recorded with the BABAR detector. We have measured four moments of the electron energy distribution and four moments of the hadronic mass distribution, each as a function of the minimum electron energy. From these moments we determine the inclusive branching fraction, the CKM matrix element |V_cb|, and other heavy quark parameters, using Heavy Quark Expansions (HQE) to order 1/m_b^3 in the kinetic mass scheme. In addition, we have studied a large sample of exclusive B^0 --> D^*- l^+ nu decays. This sample is used to extract the vector and axial form factors, the normalization and slope of the HQET form factor to determine |V_cb|.