Abstract
We report measurements of partial branching fractions for inclusive charmless semileptonic decays and the determination of the Cabibbo–Kobayashi–Maskawa (CKM) matrix element . The analysis is based on a sample of decays recorded with the BABAR detector at the PEP-II storage rings. We select events in which the decay of one of the mesons is fully reconstructed and an electron or a muon signals the semileptonic decay of the other meson. We measure partial branching fractions in several restricted regions of phase space and determine the CKM element based on different QCD predictions. For decays with a charged lepton momentum in the meson rest frame, we obtain from a fit to the two-dimensional distribution. Here, refers to the invariant mass of the final state hadron and is the invariant mass squared of the charged lepton and neutrino. From this measurement we extract as the arithmetic average of four results obtained from four different QCD predictions of the partial rate. We separately determine partial branching fractions for and decays and derive a limit on the isospin breaking in decays.
2 More- Received 5 December 2011
DOI:https://doi.org/10.1103/PhysRevD.86.032004
© 2012 American Physical Society