Hadronic Mass Moments in Inclusive Semileptonic B Meson Decays

TL;DR

This paper measures moments of the hadronic mass distribution in semileptonic B decays to extract HQET parameters and determine the CKM matrix element |V_cb| with improved precision.

Contribution

It provides the first and second moments of the hadronic mass-squared distribution and uses them to extract HQET parameters and |V_cb|, advancing the understanding of B meson decays.

Findings

First and second moments of M_X^2 measured with uncertainties.

Determination of HQET parameter lambda_1 as -0.24 +- 0.11 GeV^2.

Extraction of |V_cb| as 0.0404 +- 0.0013.

Abstract

We have measured the first and second moments of the hadronic mass-squared distribution in B -> X_c l nu, for P(lepton) > 1.5 GeV/c. We find <M_X^2 - M_D[Bar]^2> = 0.251 +- 0.066 GeV^2, < (M_X^2 -<M_X^2>)^2 > = 0.576 +- 0.170 GeV^4, where M_D[Bar] is the spin-averaged D meson mass. From that first moment and the first moment of the photon energy spectrum in b -> s gamma, we find the HQET parameter lambda_1 (MS[Bar], to order 1/M^3 and beta_0 alpha_s^2) to be -0.24 +- 0.11 GeV^2. Using these first moments and the B semileptonic width, and assuming parton-hadron duality, we obtain |V_cb| = 0.0404 +- 0.0013.