Search For B0 Decays To Invisible Final States And To Nu Nubar Gamma PDF Download
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| Total Pages | : 7 |
| Release | : 2004 |
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Download Search for B0 Decays to Invisible Final States and to Nu Nubar Gamma Book in PDF, ePub and Kindle
We establish upper limits on branching fractions for B° decays to final states where the decay products are purely invisible (i.e., no observable final state particles) and for B° decays to [nu]{bar [nu]}[gamma]. Within the Standard Model, these decays have branching fractions that are below current experimental sensitivity, but various models of physics beyond the Standard Model predict significant contributions from these channels. Using 88.5 million B{bar B} pairs collected at the [Upsilon](4S) resonance by the BABAR experiment at the PEP-II ee− storage ring at the Stanford Linear Accelerator Center, we establish upper limits at the 90% confidence level of 22 x 10−5 for the branching fraction of B° 2!invisible and 4.7 x 10−5 for the branching fraction of B° 2!{nu}{bar {nu}}[gamma].
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| Total Pages | : 8 |
| Release | : 2013 |
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Download Improved Limits on $B{̂0}$ Decays to Invisible $(+gamma)$ Final States Book in PDF, ePub and Kindle
We establish improved upper limits on branching fractions for B° decays to final states where the decay products are purely invisible (i.e., no observable final state particles) and for final states where the only visible product is a photon. Within the Standard Model, these decays have branching fractions that are below the current experimental sensitivity, but various models of physics beyond the Standard Model predict significant contributions for these channels. Using 471 million B{bar B} pairs collected at the? (4S) resonance by the BABAR experiment at the PEP-II ee− storage ring at the SLAC National Accelerator Laboratory, we establish upper limits at the 90% confidence level of 2.4 x 10−5 for the branching fraction of B° → invisible and 1.7 x 10−5 for the branching fraction of B° → invisible +?
| Author | : Dana Lindemann |
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| Release | : 2012 |
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Download The Search for Rare Non-hadronic B-meson Decays with Final-state Neutrinos Using the BaBar Detector Book in PDF, ePub and Kindle
"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." --
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| Total Pages | : 7 |
| Release | : 2010 |
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Download Search for Production of Invisible Final States in Single-Photon Decays of Upsilon(1S). Book in PDF, ePub and Kindle
We search for single-photon decays of the?(1S) resonance,? →? + invisible, where the invisible state is either a particle of definite mass, such as a light Higgs boson A°, or a pair of dark matter particles,?{bar?}. Both A° and {chi} are assumed to have zero spin. We tag?(1S) decays with a dipion transition?(2S) →??−?(1S) and look for events with a single energetic photon and significant missing energy. We find no evidence for such processes in the mass range m{sub A{sup o}} ≤ 9.2GeV and m{sub {chi}} ≤ 4.5GeV in the sample of 98 x 106?(2S) decays collected with the BABAR detector and set stringent limits on new physics models that contain light dark matter states.
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| Total Pages | : 197 |
| Release | : 2010 |
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Download A Search for the Rare Decay B0 2![gamma][gamma]. Book in PDF, ePub and Kindle
This thesis describes a search for the rare radiative decay B0 → [gamma][gamma], where the charged congugate mode is implied throughout. These decays are highly suppressed in the Standard Model where the branching fraction is expected to be of order 10-8. In some new physics scenarios this could be enhanced by up to an order of magnitude to 10-7. Therefore an observation of a significant signal above the Standard Model prediction could be a sign of new physics.
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| Total Pages | : 7 |
| Release | : 2008 |
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Download Measurement of B \to X \gamma Decays and Determination of Book in PDF, ePub and Kindle
Using a sample of 383 million B{bar B} events collected by the BABAR experiment, they measure sums of seven exclusive final states B → X{sub d(s)}[gamma], where X{sub d}(X{sub s}) is a non-strange (strange) charmless hadronic system in the mass range 0.6-1.8 GeV/c2. After correcting for unmeasured decay modes in this mass range, they obtain a branching fraction for b → d[gamma] of (7.2 ± 2.7(stat.) ± 2.3(syst.)) x 10−6. Taking the ratio of X{sub d} to X{sub s} they find [Lambda](b → d[gamma])/[Lambda](b → s[gamma]) = 0.033 ± 0.013(stat.) ± 0.009(syst.), from which they determine.
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| Total Pages | : 8 |
| Release | : 2001 |
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Download Search for the Decay B° 2!gamma-gamma Book in PDF, ePub and Kindle
We present a limit on the branching fraction for the decay B° 2![gamma][gamma] using data collected at the [Upsilon](4S) resonance with the BABAR detector at the PEP-II asymmetric--energy ee− collider. Based on the observation of one event in the signal region, out of a sample of 21.3 x 106 ee− 2 2!B{bar B} decays, we establish an upper limit on the branching fraction of [Beta] (B° 2![gamma][gamma])
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| Total Pages | : 6 |
| Release | : 2012 |
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Download Model-Independent Results for the Decay B \to L Nu(L) Gamma at BaBar Book in PDF, ePub and Kindle
We present a search for the radiative leptonic decays B+ → e?{sub e}? and B+ →?+?{sub?}? using data collected by the BABAR detector at the PEP-II B factory. We fully reconstruct the hadronic decay of one of the B mesons in?(4S) → B+B− and then search for evidence of the signal decay within the rest of the event. This method provides clean kinematic information on the signal's missing energy and high momentum photon and lepton, and allows for a model-independent analysis of this decay. Using a data sample of 465 million B-meson pairs, we obtain sensitivity to branching fractions of the same order as predicted by the Standard Model. We report a model-independent branching fraction upper limit of?(B+ → l+?{sub l}?)
| Author | : James Paul Morris |
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| Total Pages | : 153 |
| Release | : 2009 |
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Download Search for the Decay D0 -] [gamma][gamma] and Measurement of the Decay D0 -] [pi]0 [pi]0 Book in PDF, ePub and Kindle
Abstract: The Standard Model is the best current description of fundamental interactions and particles; however, the Standard Model has certain shortcomings which have driven particle physicists for the last 30 years to search for phenomena which provide evidence for the next theory beyond the Standard Model. To this end, using the BaBar detector, we search for evidence of the rare decay D* -> D0[pi];D0->[gamma][gamma]. The branching fraction of this decay is enhanced up to 200 times the standard model prediction in certain beyond-the-Standard-Model theories. A measurement of a significant branching fraction would provide evidence for a new theory of particle physics. We describe our search for this rare decay and an improved measurement of the associated decay, B(D0-> [pi]0 [pi]0) using an integrated luminosity corresponding to 470.5 fb−1 of e e− data collected by the BaBar detector at the PEP-II asymmetric ee− collider at SLAC from 1999-2007. We place an upper limit of B(D0->[gamma][gamma]) 2.51 X 10−6 at 90% confidence level and find B(D0-[pi]0[pi]0) = (8.4 " 0.1 " 0.4 " 0.3) X 10−4.
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| Total Pages | : 7 |
| Release | : 2011 |
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Download Study of B to X \gamma Decays and Determination of Book in PDF, ePub and Kindle
Using a sample of 471 million B{bar B} events collected with the BABAR detector, we study the sum of seven exclusive final states B → X{sub s(d)[gamma]}, where X{sub s(d)} is a strange (non-strange) hadronic system with a mass of up to 2.0 GeV/c2. After correcting for unobserved decay modes, we obtain a branching fraction for b → d[gamma] of (9.2 ± 2.0(stat.) ± 2.3(syst.)) x 10−6 in this mass range, and a branching fraction for b → s[gamma] of (23.0 ± 0.8(stat.) ± 3.0(syst.)) x 10−5 in the same mass range. We find [Beta](b→d[gamma])/[Beta](b→s{gamma}) = 0.040 ± 0.009(stat.) ± 0.010(syst.), from which we determine.
