Determination of |Vcb| using the semileptonic decay \bar{B}^0 --> D^{*+}e^-\bar{\nu}

TL;DR

This paper measures the CKM matrix element |Vcb| using semileptonic B meson decays at Belle, providing a precise value and branching ratio, and compares results with theoretical form factor calculations.

Contribution

First precise measurement of |Vcb| from ar{B}^0 --> D^{*+}e^-ar{ u} decays at Belle, including experimental data and theoretical comparison.

Findings

|Vcb| = (3.88+/-0.21+/-0.20+/-0.19) x 10^{-2}

Branching fraction B(ar{B}^0 --> D^{*+}e^-ar{ u}) = (4.59+/-0.23+/-0.40)%

Product |Vcb|F(1) = (3.54+/-0.19+/-0.18) x 10^{-2}

Abstract

We present a measurement of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |Vcb| using a 10.2 fb^{-1} data sample recorded at the \Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e^+e^- storage ring. By extrapolating the differential decay width of the \bar{B}^0 --> D^{*+}e^-\bar{\nu} decay to the kinematic limit at which the D^{*+} is at rest with respect to the \bar{B}^0, we extract the product of |Vcb| with the normalization of the decay form factor F(1), |Vcb |F(1)= (3.54+/-0.19+/-0.18)x10^{-2}, where the first error is statistical and the second is systematic. A value of |Vcb| = (3.88+/-0.21+/-0.20+/-0.19)x10^{-2} is obtained using a theoretical calculation of F(1), where the third error is due to the theoretical uncertainty in the value of F(1). The branching fraction B(\bar{B}^0 --> D^{*+}e^-\bar{\nu}) is measured to be (4.59+/-0.23+/-0.40)x10^{-2}.