Measurement and interpretation of moments in inclusive semileptonic decays Bbar --> X_c l- nubar

TL;DR

This paper measures moments of spectra in inclusive semileptonic B-meson decays to determine fundamental parameters like |V_cb| and quark masses using data from the BABAR detector, improving precision in heavy-quark physics.

Contribution

It provides new measurements of spectral moments and decay fractions, enabling refined extraction of CKM matrix elements and heavy-quark parameters within the Heavy Quark Expansion framework.

Findings

BR(Bbar --> X_c l- nubar) = (10.64 +/- 0.17 +/- 0.06)%

|V_cb| = (42.05 +/- 0.45 +/- 0.70) x 10^{-3}

Improved constraints on heavy-quark parameters

Abstract

We present results for the moments of observed spectra in inclusive semileptonic B-meson decays to charm hadrons Bbar --> X_c l- nubar. Moments of the hadronic-mass and the combined mass-and-energy spectra for different minimum electron or muon momenta between 0.8 and 1.9 GeV/c are obtained from a sample of 232x10^{6} Y(4S) --> B Bbar events, collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We also present a re-evaluation of the moments of electron-energy spectra and partial decay fractions BR(Bbar --> X_c e- nubar for minimum electron momenta between 0.6 and 1.5 GeV/c based on a sample of 51x10^{6} Y(4S) --> B Bbar events. The measurements are used for the extraction of the total decay fraction, the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V_cb|, the quark masses m_b and m_c, and four heavy-quark QCD parameters in the framework of a Heavy Quark Expansion (HQE). We find BR(Bbar --> X_c l- nubar) = (10.64 +/- 0.17 +/- 0.06)% and |V_cb| = (42.05 +/- 0.45 +/- 0.70) x 10^{-3}.