Results from the BaBar Fully Inclusive Measurement of $B\to X_s\gamma$

TL;DR

This paper reports on a comprehensive measurement of the inclusive $B o X_s \gamma$ decay process using BaBar data, providing photon energy spectra, branching fractions, moments, and CP asymmetry with detailed correlations.

Contribution

It introduces a lepton-tagged, fully-inclusive measurement of $B o X_s \gamma$ decays with detailed spectral and asymmetry results, including correlation matrices for theoretical fitting.

Findings

Photon energy spectrum measured in the $S$ frame.

Partial branching fractions and moments calculated for various energy thresholds.

Direct CP asymmetry measured above 2.2 GeV photon energy.

Abstract

We present preliminary results from a lepton-tagged fully-inclusive measurement of $B \to X_{s}\gamma$ decays, where $X_{s}$ is any strange hadronic state. Results are based on a BaBar data set of 88.5 million $B\bar{B}$ pairs at the $\Upsilon(4S)$ resonance. We present a reconstructed photon energy spectrum in the $\Upsilon(4S)$ frame, and partial branching fractions above minimum reconstructed photon energies of 1.9, 2.0, 2.1 and 2.2 GeV. We then convert these to measurements of partial branching fractions and truncated first and second moments of the true photon energy distribution in the B rest frame, above the same minimum photon energy values. The full correlation matrices between the first and second moments are included to allow fitting to any parameterized theoretical calculation. We also measure the direct CP asymmetry $A_{cp}(B \to X_{s+d}\gamma)$ (based on the charge of the tagging lepton) above a reconstructed photon energy of 2.2 GeV