A Study of Semileptonic B Decays And of Lepton Flavor Violating Tau Decays at BaBar PDF Download
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Languages : en
Pages : 14
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Book Description
The study of the semileptonic B decays at BABAR is presented. The results shown include measurements of the moments of hadronic-mass and electron-energy of the decay B → X{sub c}l[nu]; a determination of the.
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Category :
Languages : en
Pages : 14
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Book Description
The study of the semileptonic B decays at BABAR is presented. The results shown include measurements of the moments of hadronic-mass and electron-energy of the decay B → X{sub c}l[nu]; a determination of the.
Author:
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ISBN:
Category :
Languages : en
Pages : 11
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This article summarizes the search for lepton flavor violating [tau] and B decays, using data collected by the BABAR detector at the PEP-II asymmetric-energy B factory.
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Languages : en
Pages : 4
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Book Description
Recent results from [tau] physics studies at BABAR are presented with an emphasis on Lepton Flavour Violation measurements. The results from the current generation of B-meson Factories are already beginning to constrain the parameter space of models that go beyond the Standard Model. By the end of their data-taking, the current generation of B-meson factories will have produced nearly 2 billion [tau] pair decays. The physics potential of this legacy has only just begun to be exploited.
![Search for Lepton Flavour Violating Decays Tau -] L Ks with the BABAR Detector PDF](https://books.google.com/books/content/images/frontcover/A3dCAQAACAAJ?fife=w80-h100)
Author:
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Category :
Languages : en
Pages : 171
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Book Description
We present the search for the lepton flavour violating decay [tau] → lK°{sub s} with the BaBar experiment data. This process and many other lepton flavour violating [tau] decays, like [tau] → [mu][gamma] and [tau] → lll, are one of the most promising channel to search for evidence of new physics. According to the Standard Model and the neutrino mixing parameters, branching fractions are estimated well below 10−14, but many models of new physics allow for branching fractions values close to the present experimental sensitivity. This analysis is based on a data sample of 469fb−1 collected by BABAR detector at the PEP-II storage ring from 1999 to 2007, equivalent to 431 millions of [tau] pairs. the BABAR experiment, initially designed for studying CP violation in B mesons, has demonstrated to be one of the most suitable environments for studying [tau] decays. The tracking system, the calorimeter and the particle identification of BABAR, together with the knowledge of the [tau] initial energy, allow an extremely powerful rejection of background events that, for this analysis, is better than 10−9. Being [tau] → lK°{sub s} a decay mode without neutrinos, the signal [tau] decay can be fully reconstructed. Kinematical constraints are used in a fit that provides a decay tree reconstruction with a high resolution. For this analysis MC simulated events play a decisive role for estimating the signal efficiency and study the residual background. High statistics MC sample are produced simulating detector conditions for different periods of data collection, in order to reduce any discrepancies with the data. When discrepancies can not be removed, we perform studies to compute a correction factor or an estimation of systematic errors that need to be included in the final measurement. A significant improvement of the current result can be reached only with a higher statistics and, therefore, with a new collider providing a luminosity from 10 to 100 times more than PEP-II. A new detector, with improved performance and able to collect data in a high background environment, is also requested to fully exploit the capability of such amount of data. In fact, only keeping the efficiency and the background as similar as possible to present ones, we will be able to scale almost linearly the estimated upper limit according to the luminosity. The strong potential of improvement for the search of lepton flavour violation [tau] decays makes the building of such a machine highly desirable.
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Category :
Languages : en
Pages : 4
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We present the most recent searches for lepton-flavor-violating (LFV)? decays in BABAR. We find no evidence of? decaying to three charged leptons or to a charged lepton and a neutral meson (K{sub S}°,?,?, K*°, {bar K}*°), and set upper limits on the corresponding branching fractions (BF) between 1.8 and 19 x 10−8 at 90% confidence level (CL).
Author: Sheldon Stone
Publisher: World Scientific
ISBN: 9789810218362
Category : Science
Languages : en
Pages : 676
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Book Description
This 2nd edition is an extensive update of "B Decays?. The revisions are necessary because of the extensive amount of new data and new theoretical ideas. This book reviews what is known about b-quark decays and also looks at what can be learned in the future.The importance of this research area is increasing, as evidenced by the approval of the luminosity upgrade for CESR and the asymmetric B factories at SLAC and KEK, and the possibility of experiments at hadron colliders.The key experimental observations made thus far, measurement of the lifetimes of the different B species, B0-B0 mixing, the discovery of ?Penguin? mediated decays, and the extraction of the CKM matrix elements Vub and Vcb from semileptonic decays, as well as more mundane results, are described in great detail by the experimentalists who have been closely involved with making the measurements. Theoretical progress in understanding b-quark decays using HQET and lattice gauge techniques are described by theorists who have developed and used these techniques.Synthesizing the experimental and theoretical information, several articles discuss the implications for the ?Standard Model? and how further tests can be done using measurements of CP violation in the B system.
Author: O. Igonkina
Publisher:
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Category :
Languages : en
Pages :
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Book Description
The authors present a recent BABAR search for lepton flavor violation in tau decays. The search for {tau} {yields} {ell}{ell}{ell} ({ell} = e, {mu}) decays is based on a data sample of 91.6 fb{sup -1}. No signal is found in any of six channels and 90% CL upper limits are set in the range of (1-3) x 10{sup -7}. The search for {tau} {yields} {mu}{gamma} decay is done with a 63 fb{sup -1} data sample. The number of observed events is consistent with expected background level and a preliminary upper limit is set at 2 x 10{sup -6} at 90% CL.
Author: Michael A. Mazur
Publisher: ProQuest
ISBN: 9780549268611
Category :
Languages : en
Pages : 674
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Book Description
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.
Author:
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ISBN:
Category :
Languages : en
Pages : 4
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Book Description
Semileptonic B meson decays into final states containing the [tau] lepton are of interesting as they provide information on the Standard Model as well as a window on new physics effects. We present results on {bar B} → D{sup (*)} [tau]{bar {nu}}{sub {tau}} decays where the second B in the event is fully reconstructed.
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ISBN:
Category :
Languages : en
Pages : 359
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Book Description
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.
