Moments of the electron energy spectrum and partial branching fraction of $B \to X_c e \nu$ decays at Belle

TL;DR

This paper measures the electron energy spectrum and partial branching fractions of B meson decays at Belle, providing detailed moments and independent B+ and B0 results to improve understanding of semileptonic B decays.

Contribution

It presents the first four moments of the electron energy spectrum and independent B+ and B0 partial branching fractions at specific energy thresholds in B meson decays.

Findings

First four moments of electron energy spectrum measured.

Partial branching fractions for B+ and B0 decays determined.

Independent measurements at 0.4 and 0.6 GeV thresholds provided.

Abstract

We report a measurement of the inclusive electron energy spectrum for charmed semileptonic decays of B mesons in a 140fb-1 data sample collected at the \Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+ e- collider. We determine the first four moments of the electron energy spectrum for threshold values of the electron energy between 0.4 and 2.0 GeV. In addition, we provide values of the partial branching fraction (zeroth moment) for the same electron threshold energies, and independent measurements of the B+ and B0 partial branching fractions at 0.4 GeV and 0.6 GeV electron threshold energies. We measure the independent B+ and B^0 partial branching fractions with electron threshold energies of 0.4 GeV to be \Delta \mathcal{B} (B+ -> X_c e \nu)=(10.79 +/- 0.25(stat.) +/- 0.27(sys.))% and \Delta \mathcal{B} (B0 -> X_c e \nu)=(10.09 +/- 0.30(stat.) +/- 0.22(sys.))%. Full correlations between all measurements are evaluated.