Measurement of the inclusive electron spectrum from B meson decays and determination of |Vub |

(B a B ar Collaboration)

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25 Scopus citations

Abstract

Based on the full BABAR data sample of 466.5 million BB pairs, we present measurements of the electron spectrum from semileptonic B meson decays. We fit the inclusive electron spectrum to distinguish Cabibbo-Kobayashi-Maskawa (CKM) suppressed B→Xueν decays from the CKM-favored B→Xceν decays, and from various other backgrounds, and determine the total semileptonic branching fraction B(B→Xeν)=(10.34±0.04stat±0.26syst)%, averaged over B± and B0 mesons. We determine the spectrum and branching fraction for charmless B→Xueν decays and extract the CKM element |Vub|, by relying on four different QCD calculations based on the heavy quark expansion. While experimentally, the electron momentum region above 2.1 GeV/c is favored, because the background is relatively low, the uncertainties for the theoretical predictions are largest in the region near the kinematic endpoint. Detailed studies to assess the impact of these four predictions on the measurements of the electron spectrum, the branching fraction, and the extraction of the CKM matrix element |Vub| are presented, with the lower limit on the electron momentum varied from 0.8 GeV/c to the kinematic endpoint. We determine |Vub| using each of these different calculations and find, |Vub|=(3.794±0.107exp -0.219 SF+0.292 -0.068 theory+0.078)×10-3 (De Fazio and Neubert), (4.563±0.126exp -0.208 SF+0.230 -0.163 theory+0.162)×10-3 (Bosch, Lange, Neubert, and Paz), (3.959±0.104exp -0.154 SF+0.164 -0.079 theory+0.042)×10-3 (Gambino, Giordano, Ossola, and Uraltsev), (3.848±0.108exp -0.070 theory+0.084)×10-3 (dressed gluon exponentiation), where the stated uncertainties refer to the experimental uncertainties of the partial branching fraction measurement, the shape function parameters, and the theoretical calculations.

Original languageEnglish
Article number072001
JournalPhysical Review D
Volume95
Issue number7
DOIs
StatePublished - 1 Apr 2017

Funding

FundersFunder number
Bundesministerium fur Bildung und Forschung and Deutsche Forschungsgemeinschaft
National Science Foundation1404070
National Science Foundation
U.S. Department of Energy
Alfred P. Sloan Foundation
Natural Sciences and Engineering Research Council of Canada
Science and Technology Facilities CouncilST/N000420/1
Science and Technology Facilities Council
Marie Curie
European Commission
Stichting voor Fundamenteel Onderzoek der Materie
Ministerio de Economía y Competitividad
Ministry of Education and Science of the Russian Federation
Instituto Nazionale di Fisica Nucleare
Norges Forskningsråd
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
Institut National de Physique Nucléaire et de Physique des Particules

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