Study of Exclusive Semileptonic B Meson Decays ToTau Leptons
Study of Exclusive Semileptonic B Meson Decays ToTau Leptons

Author:

Publisher:

Published: 2007

Total Pages: 359

ISBN-13:

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We present the results of a search for four exclusive semileptonic decays B → D{sup (*)}[tau]−{bar [nu]}{sub [tau]} in 209 fb−1 of data collected with the BABAR detector, corresponding to 232 million e+e- → [Upsilon](4S) → B{bar B} events. We select events with a D{sup (*)} meson and a light lepton (e or [mu]) recoiling against a fully-reconstructed B meson. We perform a fit to the lepton spectrum and missing mass squared to discriminate signal events from backgrounds, predominantly B → D{sup (*)}{tau}−{bar [nu]}{sub {tau}}. A control sample of identified D**l−{bar {nu}}{sub {ell}} events is included in the fit to estimate the background contribution from these decays. We measure [beta](B → D{sub {tau}{nu}}) = (0.86±0.24±0.11±0.06)% and [beta](B → D*{sub {tau}{nu}}) = (1.62±0.31±0.10±0.05)%, where the errors are statistical, systematic, and normalization-mode related, respectively, and where the results are expressed for the {bar B}° lifetime.

Study of Exclusive Semileptonic B Meson Decays to Tau Leptons
Study of Exclusive Semileptonic B Meson Decays to Tau Leptons

Author: Michael A. Mazur

Publisher: ProQuest

Published: 2007

Total Pages: 674

ISBN-13: 9780549268611

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We present the results of a search for four exclusive semileptonic decays B & rarr; D(*)tau -nutau in 209 fb -1 of data collected with the BABAR detector, corresponding to 232 million e+e - & rarr; Upsilon(4S) & rarr; B B events. We select events with a D (*) meson and a light lepton (e or mu) recoiling against a fully-reconstructed B meson. We perform a fit to the lepton spectrum and missing mass squared to discriminate signal events from backgrounds, predominantly B & rarr; D (*) & ell;-nu & ell; . A control sample of identified D** & ell;- nu & ell; events is included in the fit to estimate the background contribution from these decays. We measure B (B & rarr; Dtaunu) = (0.86+/-0.24+/-0.11+/-0.06)% and B (B & rarr; D*taunu) = (1.62+/-0.31+/-0.10+/-0.05)%, where the errors are statistical, systematic, and normalization-mode related, respectively, and where the results are expressed for the B0 lifetime.

Leptonic Decays of the Charged B Meson
Leptonic Decays of the Charged B Meson

Author: Luke Andrew Corwin

Publisher:

Published: 2008

Total Pages: 148

ISBN-13:

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Abstract: We present a search for the decay of the charged B meson into a charged lepton and a neutrino 458.9 million Upsilon(4S) decays recorded with the Babar detector at the SLAC PEP-II B-Factory. A sample of events with one reconstructed exclusive semileptonic B decay is selected, and in the recoil a search for the signal decay is performed. The tau lepton is identified in decays to an electron and two neutrinos; a muon and two neutrinos; a charged pion and a neutrino; or a charged pion, a neutral pion, and a neutrino. The analysis strategy and the statistical procedure is set up for branching fraction extraction or upper limit determination. We determine from the data set a preliminary measurement of the branching fraction a charged B decaying to a tau lepton and a neutrino = (1.8 " 0.8 " 0.1)E-4, which excludes zero at 2.4 standard deviations. We extract the B meson decay constant = 255 " 58 MeV. Combination with the hadronically tagged measurement yields (1.8 " 0.6)E-4. We also set preliminary limits on the branching fraction of charged B decaying to an electron and a neutrino at 7.7E-6 and the charged B decaying to a muon and a neutrino at 11E-6. The limits are at the 90% confidence level.