Measurements of Moments of the Hadronic Mass Distribution in Semileptonic B Decays

Abstract

We report a measurement of the first four moments of the hadronic mass distribution in B --> X_c lv decays. The measurements are based on 89 million Upsilon(4S) --> BBbar events where the hadronic decay of one of the B mesons is fully reconstructed and a charged lepton from the decay of the other B meson is identified. The moments are presented for minimum lepton momenta ranging from 0.9 to 1.6 GeV in the B rest frame. It is expected that such measurements will lead to improved determinations of |V_{cb}| and |V_{ub}|.

Figures (3)

• Figure 1: $M_X$ distributions after subtraction of the $B_{\rm reco}$ background, for (a) $p^*_{\rm min} = 0.9~\mathrm{\,Ge V}\xspace$, and (b) $p^*_{\rm min} = 1.6~\mathrm{\,Ge V}\xspace$. The Monte Carlo prediction for decays to $D$ and $D^*$ is indicated by the open histogram, the small residual background by the solid histogram.
• Figure 2: Results of the $\langle M_X \rangle$ calibration procedure. The calibration data and fit results are shown by the lower dashed line (circles), the verification by the upper solid line (triangles).
• Figure 3: Measured moments (a) $\langle M_X \rangle$, (b) $\langle M_X^2 \rangle$, (c) $\langle M_X^3 \rangle$, and (d) $\langle M_X^4 \rangle$ for different lepton momenta, $p^*_{\rm min}$. The bars indicate the statistical and total errors. The individual moments are highly correlated.