A Measurement of the Branching Fraction for the Inclusive B --> X(s) gamma Decays with the Belle Detector

Abstract

We have measured the branching fraction of the inclusive radiative B meson decay B --> X(s) gamma to be Br(B->X(s)gamma)=(3.36 +/- 0.53(stat) +/- 0.42(sys) +0.50-0.54(th)) x 10^{-4}. The result is based on a sample of 6.07 x 10^6 BBbar events collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e^+e^- storage ring.

Figures (5)

• Figure 1: The distribution of the SFW variable described in the text. The off-resonance background data (solid circles) and the $q\bar{q}$ MC expectation (open histogram) are compared with the signal distribution of $B{\to}D\pi$ data (open circles) and signal MC (hatched histogram).
• Figure 2: The beam constrained mass ($M_{bc}$) distribution (a) compared with the total background $q\bar{q}$ and $b{\to}c$ (open histogram); (b) after background subtraction compared with the signal MC expectation (hatched histogram).
• Figure 3: The ratio of the background events in the SFW signal region to the sideband region as a function of $M_{bc}$ from the $q\bar{q}$ MC (solid circles) and off-resonance data (open circles).
• Figure 4: The recoil mass ($M_{X_s}$) distribution after background subtraction compared with the signal MC expectation (hatched histogram).
• Figure 5: The photon energy spectrum, background subtracted and corrected for the cut-off on $M_{X_s}$. The data points are compared with signal MC expectations for three different values of $m_b$.