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Title: Measurement of |V(Ub)| Using Inclusing Semileptonic B Meson Decays

Abstract

This dissertation presents a measurement of the CKM matrix element |V{sub ub}| made with a sample of 64 million B{bar B} events collected with the BABAR detector. Using Heavy Quark theory, we combine the observed yield of leptons from semileptonic B decay in the electron energy interval 2.1-2.6 GeV with a recent CLEO measurement of the B {yields} X{sub s}{gamma} photon spectrum to find |V{sub ub}| = (4.25 {+-} 0.35 {+-} 0.45 {+-} 0.20) x 10{sup -3}, where the first uncertainty is experimental and the last two are from theory.

Authors:
;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
878092
Report Number(s):
SLAC-R-784
TRN: US200611%%156
DOE Contract Number:
AC02-76SF00515
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; B MESONS; DECAY; ELECTRONS; LEPTONS; MATRIX ELEMENTS; PHOTONS; QUARKS; Experiment-HEP,HEPEX

Citation Formats

Kim, Hojeong, and /Texas U. Measurement of |V(Ub)| Using Inclusing Semileptonic B Meson Decays. United States: N. p., 2006. Web. doi:10.2172/878092.
Kim, Hojeong, & /Texas U. Measurement of |V(Ub)| Using Inclusing Semileptonic B Meson Decays. United States. doi:10.2172/878092.
Kim, Hojeong, and /Texas U. Fri . "Measurement of |V(Ub)| Using Inclusing Semileptonic B Meson Decays". United States. doi:10.2172/878092. https://www.osti.gov/servlets/purl/878092.
@article{osti_878092,
title = {Measurement of |V(Ub)| Using Inclusing Semileptonic B Meson Decays},
author = {Kim, Hojeong and /Texas U.},
abstractNote = {This dissertation presents a measurement of the CKM matrix element |V{sub ub}| made with a sample of 64 million B{bar B} events collected with the BABAR detector. Using Heavy Quark theory, we combine the observed yield of leptons from semileptonic B decay in the electron energy interval 2.1-2.6 GeV with a recent CLEO measurement of the B {yields} X{sub s}{gamma} photon spectrum to find |V{sub ub}| = (4.25 {+-} 0.35 {+-} 0.45 {+-} 0.20) x 10{sup -3}, where the first uncertainty is experimental and the last two are from theory.},
doi = {10.2172/878092},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Mar 24 00:00:00 EST 2006},
month = {Fri Mar 24 00:00:00 EST 2006}
}

Technical Report:

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  • The authors present a preliminary determination of the CKM matrix element |V{sub ub}| based on the analysis of semileptonic B decays from a sample of 88 million {Upsilon}(4S) decays collected with the BaBar detector at the e{sup +}e{sup -} storage ring. Charmless semileptonic B decays are selected using the electron energy E-e and the invariant mass q{sup 2} of the electron-neutrino pair. The neutrino meomentum is inferred from a measurement of the visible energy and momentum in the detector and knowledge of the e{sup +}e{sup -} beam momenta. The partial branching fraction is determined in a region of the q{supmore » 2}-E-e plane where semileptonic B decays to charm are highly suppressed. The total charmless semileptonic branching fraction is extracted using a theoretical calculation based on the heavy quark expansion. Preliminary results yield |V{sub ub}| = (4.57 {+-} 0.21 {+-} 0.25 {+-} 0.34 + 0.59 - 0.29 {+-} 0.22) x 10{sup -3} where the uncertainties are from statistics (data and MC), detector modeling, background modeling, the shape function, and the heavy quark operator product expansion, respectively.« less
  • The authors study the inclusive electron spectrum of B --> X{sub u}e{nu} decays near the kinematic limit for B --> X{sub c}e{nu} transitions using a sample of 88 million {Upsilon}(4S) decays recorded by the BABAR detector at the PEP II e{sup +}e{sup -} storage rings. For the electron momentum interval of 2.0-2.6GeV/c the partial branching fraction is measured to be {Delta}B(B --> X{sub u}e{nu}) = (0.480 {+-} 0.029(stat) {+-} 0.053(syst) x 10{sup -3}). Combining this result on {Delta}B with measurements of the inclusive photon spectrum in B --> X{sub s}{gamma} transition the authors find |V{sub ub}| = 3.94 {+-} 0.25expmore » {+-} 0.37 f{sub u} {+-} 0.19 theory x 10{sup -3}, where the first error represents the combined statistical and systematic experimental uncertainty of the partial branching fraction measurement, the second refers to the uncertainty of the determination of the fraction f{sub u} of the inclusive electron spectrum that falls within the cuts, and the third error is due to theoretical uncertainties in the QCD corrections, plus the uncertainty in the b-quark mass. All results are preliminary.« less
  • The determination of |V{sub ub}| from inclusive semileptonic B decays is limited by uncertainties in modeling the decay distributions in b {yields} u{ell}{nu} transitions. The largest uncertainties arise from the limited knowledge of the appropriate b quark mass and Fermi momentum to use in the parameterization of the shape function. This paper presents a new method in which these shape function parameters are constrained by the same data used to measure |V{sub ub}|. The method requires measurements of the momenta of both the charged lepton and the neutrino in semileptonic B decays. From these quantities two complementary observables can bemore » constructed, one for discriminating between b {yields} u{ell}{nu} transitions and background and the other for constraining the shape function. Using this technique the uncertainties in |V{sub ub}| from the shape function may be significantly reduced.« less