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Title: Measurement of the inclusive electron spectrum from B meson decays and determination of | V u b |

Based on the full BABAR data sample of 466.5 million $$B\bar{B}$$ 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 → X ueν decays from the CKM-favored B → X ceν decays, and from various other backgrounds, and determine the total semileptonic branching fraction B (B → Xeν) = ( 10.34 ± 0.04 stat ± 0.2 6 syst)%, averaged over B ± and B 0 mesons. We determine the spectrum and branching fraction for charmless B → X ueν decays and extract the CKM element | V ub| , 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 |V ub| are presented, with the lower limit on the electron momentum varied from 0.8 GeV / c to the kinematic endpoint. We determine |V ub| using each of these different calculations and find, |V ub| = ( 3.794 ± 0.107 exp $$+ 0.292\atop{ - 0.219 SF}$$ $$+ 0.078 \atop{- 0.068 theory}$$ ) × 10 - 3 (De Fazio and Neubert), (4.563 ± 0.126 exp $$+ 0.230\atop {- 0.208 SF}$$ $$+ 0.162\atop{- 0.163 theory}$$ ) ×10 -3 (Bosch, Lange, Neubert, and Paz), (3.959 ± 0.104 exp $$+ 0.164\atop{- 0.154 SF}$$ $$+ 0.042\atop{ - 0.079 theory}$$ ) × 10 -3 (Gambino, Giordano, Ossola, and Uraltsev), (3.848 ± 0.108 exp $$+ 0.084\atop{ - 0.070 theory}$$) × 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.
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Publication Date:
Grant/Contract Number:
AC02-76SF00515; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 95; Journal Issue: 7; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Contributing Orgs:
BaBar Collaboration
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
1393215
Alternate Identifier(s):
OSTI ID: 1349966; OSTI ID: 1361064