A Search for the Rare Leptonic B Decay B to Tau Nu Recoiling Against B to Dstar-zero 1 Nu
Author : Mousumi Datta
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Page : 220 pages
File Size : 40,33 MB
Release : 2005
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Search for the Rare Leptonic Decay B- -] Tau- Nubar
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Page : pages
File Size : 24,7 MB
Release : 2004
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Book Description
We present a search for the decay B[sup -] [yields] [tau][sup -] [bar [nu]][sub [tau]] in a sample of 88.9 x 10[sup 6] B[bar B]pairs recorded with the BABAR detector at the SLAC B-Factory. One of the two B mesons from the [Upsilon](4S) is reconstructed in a hadronic or a semileptonic final state and the decay products of the other B in the event are analyzed for consistency with a B[sup -] [yields] [tau][sup -] [bar [nu]][sub [tau]] decay. We find no evidence of a signal and set an upper limit on the branching fraction of [Beta](B[sup -] [yields] [tau][sup -] [bar [nu]][sub [tau]])
Search for the Rare Leptonic Decay B+ -] Mu+ Nu[sub Mu].
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Page : pages
File Size : 27,31 MB
Release : 2004
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We have performed a search for the rare leptonic decay B[sup +] [yields] [mu][sup +][nu][sub [mu]] with data collected at the [Upsilon](4S) resonance by the BABAR experiment at the PEP-II storage ring. In a sample of 88.4 million B[bar B] pairs, we find no significant evidence for a signal and set an upper limit on the branching fraction [Beta](B[sup +] [yields] [mu][sup +] [nu][sub [mu]])
Search for the Rare Leptonic Decays B+̂ \to L+̂ \nu_l (l
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Page : 8 pages
File Size : 48,2 MB
Release : 2009
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We have performed a search for the rare leptonic decays B → l+?{sub l}({ell} = e,?), using data collected at the?(4S) resonance by the BABAR detector at the PEP-II storage ring. In a sample of 468 x 106 B{bar B} pairs we find no evidence for a signal and set an upper limit on the branching fractions B(B+ → e+?{sub e})
A Search for the Rare and Forbidden Decays D0 2!V L+ L-
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Page : 105 pages
File Size : 25,62 MB
Release : 2003
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I report the results of a search for flavor-changing neutral current, leptonflavor, and lepton-number violating decays of the 3 and 4-body decay modes of the D0 (and its antiparticle) containing muons and electrons. Using data from Fermilab charm hadroproduction experiment E791, I examine modes with two leptons and either a [rho]0, $\bar{K}$0, or [Phi] vector meson or a non-resonant [pi][pi], K[pi], or KK pair of pseudoscalar mesons. No evidence for any of these decays is found. Therefore, branching-fraction upper limits, typically at the 10-4 level, are presented at the 90% confidence level for the 27 decay modes examined. Of these searches, 18 are investigations of decays without previous published results; several others have significantly improved sensitivity over previous results.
The Search for Rare Non-hadronic B-meson Decays with Final-state Neutrinos Using the BaBar Detector
Author : Dana Lindemann
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Page : pages
File Size : 20,1 MB
Release : 2012
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"This thesis presents the searches for two rare B meson decays: the radiative leptonic decay B+ -> l+ nu gamma (l = e, mu) and the flavor-changing neutral current B -> K(*) nu nubar. These searches use the full dataset collected by the BaBar experiment, which corresponds to almost 500 million BB pairs. After fully reconstructing the hadronic decay of one of the B mesons in Upsilon(4S) -> BB decays, evidence of B+ -> l+ nu gamma or B -> K(*) nu nubar is looked for in the rest of the event. No significant evidence of either signal decay is observed. Model-independent branching-fraction upper limits are set at BR(B ->e nu gamma)17 x10 {-6}, BR(B -mu nu gamma)24 x10 {-6}, and BR(B -l nu gamma)15.6 x10 {-6}, all at the 90% confidence level. These are currently the most stringent published upper limits for B+ - l+ nu gamma. In addition, branching-fraction upper limits are set at BR(B -> K+ nu nubar)3.7 x10 {-5}, BR(B - K0 nu nubar)8.0 x10 {-5}, BR(B - K*+ nu nubar)11.5 x10 {-5}, and BR(B - K*0 nu nubar)9.2 x10 {-5}, all at the 90% confidence level. For additional sensitivity to New Physics contributions, partial B - K(*) nu nubar branching-fraction upper limits are also determined over the full kinematic range." --
Search for the Rare Decay B -] K Nu Nubar
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Page : 10 pages
File Size : 39,1 MB
Release : 2010
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We present a search for the rare decays B → K+?{bar?} and B° → K°?{bar?} using 459 million B{bar B} pairs collected with the BABAR detector at the SLAC National Accelerator Laboratory. Flavor-changing neutral-current decays such as these are forbidden at tree level but can occur through one-loop diagrams in the Standard Model (SM), with possible contributions from new physics at the same order. The presence of two neutrinos in the final state makes identification of signal events challenging, so reconstruction in the semileptonic decay channels B → D{sup (*)}l? of the B meson recoiling from the signal B is used to suppress backgrounds. We set an upper limit at the 90% confidence level of 1.3 x 10−5 on the total branching fraction for B+ → K+?{bar {nu}}, and 5.6 x 10−5 for B° → K°{nu}{bar {nu}}. We additionally report partial branching fractions in two ranges of di-neutrino mass squared for B+ → K+{nu}{bar {nu}}.
Leptonic Decays of the Charged B Meson
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Page : 176 pages
File Size : 43,11 MB
Release : 2008
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We present a search for the decay B+ 2!l+[nu] (= [tau], [mu], or e) in (458.9±5.1)×106 [Upsilon](4S) decays recorded with the BABAR detector at the SLAC PEP-II B-Factory. A sample of events with one reconstructed exclusive semi-leptonic B decay (B- 2!D0l -$\bar{v}$X) is selected, and in the recoil a search for B+ 2! +[nu]l signal is performed. The [tau] is identified in the following channels: [tau]+ 2!e+[nu]e$\bar{v}$[tau], [tau]+ 2![mu]+[nu][mu]$\bar{v}$[tau], [tau]+ 2![pi]+$\bar{v}$[tau], and [tau]+ 2![pi]+[pi]0$\bar{v}$[tau] . The analysis strategy and the statistical procedure is set up for branching fraction extraction or upper limit determination. We determine from the dataset a preliminary measurement of B(B+ 2![tau]+[nu][tau]) = (1.8 ± 0.8 ± 0.1) × 10-4, which excludes zero at 2.4[sigma], and fB = 255 ± 58 MeV. Combination with the hadronically tagged measurement yields B(B+ 2![tau]+[nu][tau]) = (1.8 ± 0.6) × 10-4. We also set preliminary limits on the branching fractions at B(B+ 2!e+[nu]e)
A Search for the Decays B+ Arrow] L+nu and B[degree]arrow L+ Tau- (l
Author : Miika A. Klemetti
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Page : pages
File Size : 14,62 MB
Release : 2007
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"We present searches for the leptonic decays B + [arrow] l+nu and the lepton flavor violating decays B[degree][arrow] l[symbol][tau][symbol], where l = e, [mu], with data collected by the BABAR experiment at SLAC. These searches utilize a technique in which we fully reconstruct the accompanying B̄ in [Upsilon](4S)[arrow] BB̄ events, and look for a monoenergetic lepton in the signal B frame. The signal yield in the data is extracted from a fit to the signal lepton candidate momentum distribution in the signal B rest frame. Using a data sample of approximately 378 million BB̄ pairs (342 fb-1), we find no evidence of signal in any of the decay modes. Branching fraction upper limits of B (B+[arrow] e +[nu])
Searches for the Decays B0 to L+- Tau-+ and B+ to L+ Nu(L
Author :
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Page : 8 pages
File Size : 29,80 MB
Release : 2008
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Book Description
We present searches for the leptonic decays B → l+? and the lepton flavor violating decays B° → l{sup {+-}}?{sup {-+}}, where l = e,?, with data collected by the BABAR experiment at SLAC. This search demonstrates a novel technique in which we fully reconstruct the accompanying {bar B} in?(4S) → B{bar B} events, and look for a monoenergetic lepton from the signal B decay. The signal yield is extracted from a fit to the signal lepton candidate momentum distribution in the signal B rest frame. Using a data sample of approximately 378 million B{bar B} pairs (342 fb−1), we find no evidence of signal in any of the decay modes. Branching fraction upper limits of?(B+ → e+?)
