Download or read book Rare B Meson Decays Involving Leptons at BaBar written by and published by . This book was released on 2013 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Search for Rare Non hadronic B meson Decays with Final state Neutrinos Using the BaBar Detector written by Dana Lindemann and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "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." --

Download or read book Rare And Radiative B Meson Decays From the BaBar Experiment written by J. Stelzer and published by . This book was released on 2006 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its start in 1999 the BABAR experiment has collected a vast amount of data. Electron-positron collisions at the energy of the {Upsilon}(4S) resonance have produced about 240 million coherent B{sup 0}{bar B}{sup 0} and B{sup +}B{sup -} pairs, opening the doors for exploration of rare B meson decays. An overview of the electroweak penguin physics program of BABAR is given, the analysis of two specific decays is presented in detail.

Download or read book Study of the Rare Decay B Mesons Decaying to X Mesons Positive And Negative Leptons at BABAR written by Ventzislav B. Koptchev and published by . This book was released on 2005 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flavor-changing neutral current transitions are forbidden at tree level in the Standard Model and can only occur via higher order diagrams. Since the amplitudes for such loops are dominated by the heaviest known particles, and non-SM effects are expected to contribute at the same order as the SM, such processes are an ideal place to look for new physics. We present a measurement of the inclusive branching fraction for the flavor-changing neutral current process B {yields} X{sub s}{ell}{sup +}{ell}{sup -} with a sample of 81.9 fb{sup -1}, collected with the BABAR detector at the Stanford Linear Accelerator Center. The final state is reconstructed from e{sup +}e{sup -} or {mu}{sup +}{mu}{sup -} pairs and a hadronic system consisting of one K{sup {+-}} or K{sub s} and up to two pions, with at most one {pi}{sup 0}. They observe a signal of 40 {+-} 10(stat) {+-} 2(syst) events and extract a branching fraction {Beta}(B {yields} X{sub s}{ell}{sup +}{ell}{sup -}) = (5.6 {+-} 1.5(stat) {+-} 0.6(exp. syst) {+-} 1.1(model syst)) x 10{sup -6} for m{sub ll}> 0.2 GeV.

Download or read book Rare Decays And Exotic States With BaBar written by S. H. Robertson and published by . This book was released on 2006 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results from the BABAR experiment are presented for searches for several rare FCNC B and D meson decays, including the modes B{sup 0} {yields} {ell}{sup +}{ell}{sup -} and D{sup 0} {yields} {ell}{sup +}{ell}{sup -}, B {yields} ({rho}, {omega}){gamma} and B{sup +} {yields} (K, {pi}){sup +}{nu}{bar {nu}}. Limits on lepton flavor violation in neutrino-less {tau} decays are also discussed. Finally, results of BABAR searches for the strange pentaquark states {Theta}{sup +}(1540), {Xi}{sup --}(1860) and {Xi}{sup 0}(1860) are summarized.

Download or read book Rare B Decays at BaBar written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present recent results on rare B meson decays based on data taken by the BABAR detector at the PEP-II asymmetric ee− collider. Included in this report are measurements of branching fractions and other quantities of interest for several hadronic, radiative, electroweak, and purely leptonic decays of B mesons.

Download or read book Search for the Rare Decay of a B Meson Into a Lambda Baryon Proton and Neutrino antineutrino Pair at the BABAR and Belle II Experiments written by Robert Seddon and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "We present two analyses of the rare B- -> Lambda pbar nu nubar decay. Within the Standard Model, the process B- -> Lambda pbar nu nubar is permitted but highly suppressed, with an expected branching fraction of (7.9 +/- 1.9) x 10^-7. This rarity makes it a sensitive probe for the existence of new physics, which may be discoverable in the form of a higher than predicted branching fraction.The first analysis is conducted on data collected at the BABAR experiment, which ran from 1999-2008. BABAR collected 433 fb^-1 of integrated luminosity at the Upsilon(4S) resonance; Upsilon(4S) decays almost exclusively into B-Bbar pairs, and this analysis uses hadronic tag reconstruction to fully reconstruct one of the B-mesons in this pair. The search for B- -> Lambda pbar nu nubar is then conducted among the decay products of the second, unreconstructed B-meson. Using both real data and Monte Carlo simulations, we develop and implement a signal selection that selects candidates conforming to the expected characteristics of B- -> Lambda pbar nu nubar decays. The result of the analysis is an upper limit on the branching fraction at the 90% confidence level of 3.02 x 10^-5. This is the world's first experimental result in the search for B- -> Lambda pbar nu nubar decays.The second analysis is conducted on Monte Carlo simulations of data that will be collected at Belle II, the world's only next-generation B-meson facility. Over its lifetime Belle II will collect 50 ab^-1 of data, approximately 100 times that of BABAR. This increase in data, along with more capable hardware and software, should allow Belle II to search for B- -> Lambda pbar nu nubar decays with greater sensitivity than BABAR. Using a simulated dataset equivalent in size to that used in our BABAR study, we employ Full Event Interpretation to fully reconstruct the decay of one B-meson in each B-Bbar pair, and conduct our signal selection in the remainder of the data. The result of the analysis is a predicted upper limit on the branching fraction at the 90% confidence level of 1.2 x 10^-4. A comparison of the Belle II and BABAR results highlights several areas where Belle II will need to improve in order to make best use of its projected dataset"--

Download or read book Study of Rare B Meson Decays Related to the CP Observable Sin 2 beta gamma at the BABAR Experiment written by Toyoko Jennifer Orimoto and published by . This book was released on 2006 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Muon flavored Pure Leptonic Decay of the Charged B Meson at the BABAR Experiment written by C. Jess Riedel and published by . This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Leptonic Decays of the Charged B Meson written by Luke Andrew Corwin and published by . This book was released on 2008 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Rare B Meson Decays With Omega Mesons written by Lei Zhang and published by . This book was released on 2006 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rare charmless hadronic B decays are particularly interesting because of their importance in understanding the CP violation, which is essential to explain the matter-antimatter asymmetry in our universe, and of their roles in testing the ''effective'' theory of B physics. The study has been done with the BABAR experiment, which is mainly designed for the study of CP violation in the decays of neutral B mesons, and secondarily for rare processes that become accessible with the high luminosity of the PEP-II B Factory. In a sample of 89 million produced B{bar B} pairs on the BABAR experiment, we observed the decays B{sup 0} {yields} {omega}K{sup 0} and B{sup +} {yields} {omega}{rho}{sup +} for the first time, made more precise measurements for B{sup +} {yields} {omega}h{sup +} and reported tighter upper limits for B {yields} {omega}K* and B{sup 0} {yields} {omega}{rho}{sup 0}.

Download or read book Study of B Meson Decays to Ppbarh Final States written by Tetiana B. Hryn'ova and published by . This book was released on 2006 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: B mesons are unique among well-established non-quarkonium mesons in their ability to decay into baryons. Baryonic B decays offer a wide range of interesting areas of study: they can be used to test our theoretical understanding of rare decay processes involving baryons, search for direct CP violation and study low-energy QCD. This thesis presents measurements of branching fractions and a study of the decay dynamics of the charmless three-body decays of B meson into p{bar p}h final states, where h = {pi}{sup +}, K{sup +}, K{sub S}{sup 0}, K*{sup 0} or K*{sup +}. With a sample of 232 million {Upsilon}(4S) {yields} B{bar B} events collected with the BaBar detector, we report the first observation of the B {yields} p{bar p}K*{sup 0} decay, and provide improved measurements of branching fractions of the other modes. The distribution of the three final-state particles is of particular interest since it provides dynamical information on the possible presence of exotic intermediate states such as the hypothetical pentaquark states {Theta}*{sup ++} and {Theta}{sup +}in the m{sub pK{sup +}} and m{sub pK{sub S}{sup 0}} spectra, respectively, or glueball states (such as the tensor glueball f{sub J}(2220)) in the m{sub p{bar p}} spectrum. No evidence for exotic states is found and upper limits on the branching fractions are set. An enhancement at low p{bar p} mass is observed in all the B {yields} p{bar p}h modes, and its shape is compared between the decay modes and with the shape of the time-like proton form factor. A Dalitz plot asymmetry in B {yields} p{bar p}K{sup +} mode suggests dominance of the penguin amplitude in this decay and disfavors the possibility that the low mass p{bar p} enhancement originates from the presence of a resonance below threshold (such as the recently seen baryonium candidate at 1835 MeV/c{sup 2}). We also identify decays of the type B {yields} X{sub c{bar c}}h {yields} p{bar p}h, where h = K{sup +}, K{sub S}{sup 0}, K*{sup 0} or K*{sup +}, and X{sub c{bar c}} = {eta}{sub c} or J/{psi}. In particular, we report on the evidence of the B {yields} {eta}{sub c}K*{sup +} decay and provide a measurement of the width of {eta}{sub c}.

Download or read book Search for the Rare Decay B u2192 l l in the BaBar Experiment written by and published by . This book was released on 2006 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rare decay B → ?ll- is the simplest manifestation of a b → dl+l- flavor-changing neutral current (FCNC) process. This type of process only proceeds through penguin loop or box diagrams and is sensitive to physics at the electroweak scale. It can be used to constrain parameters of the Standard Model and its extensions. B → ?l+l- events have not yet been observed; the branching fraction is expected to be an order of magnitude smaller than the measured branching fraction for the similar B → Kl+l- decay. Using 230 million B$ar{B}$ meson pairs collected with the BABAR detector, we have done a search for the rare decay B →?l+l- . The data was produced in e+e- collision at the Y(4S) resonance in the PEP-II collider between 1999 and 2004. Four exclusive B-meson decay modes have been reconstructed: B+ → ?+l+l- and B0 → ?0l+l- , where l+ l- is either an electron pair (e+e-) or a muon pair (?+?-). We find no evidence for a signal, and we obtain upper limits on the branching fractions ?. Assuming the isospin relation ?(B+ → ?+l+l- ) 2 x ?B+/?B0 ?(B0 → ?0l+l-), we obtain an upper limit at 90% confidence level on the lepton-flavor-averaged branching fraction of B → ?l+l- to be ?(B → ?e?) 9.2 x 10sup-8 /supat 90% C.L. We have also reconstructed two control modes Bsup+/sup→ ?sup+/supesup±/sup?sup±/sup and Bsup0/sup → ?sup0/supesup±/sup?sup±/sup and we also obtain an upper limit at 90% confidence level on the lepton-flavor-violating decay B → ?e? of ?(B → ?e?) 9.2 x 10

Download or read book Study of Rare B Meson Decays Related to the CKM Angle Beta at BaBar written by and published by . This book was released on 2007 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Results on Leptonic B Meson Decays at BaBar written by and published by . This book was released on 2008 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present selected new results on leptonic B meson decays from the BABAR experiment: searches for the decays B° → ll−, B+ → l+? and B° → l+?−, and B → K?{bar {nu}}, where l = e or?. They observe no evidence for these decays and set upper limits on their branching fractions.

Download or read book Rare Semi leptonic B Meson Decays written by James David Lyon and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Search for the Decay of a B Meson Into a Kaon and a Tau Lepton Pair at the BaBar Experiment written by Racha Cheaib and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The flavour changing neutral current (FCNC) process , B+ → K+ [tau]+[tau]−, is highly sup-pressed in the Standard Model (SM). This decay is forbidden at tree level and only occursat lowest order via one-loop diagrams. B+ → K+ [tau]+[tau]− thus has the potential to providea stringent test of the SM and a fertile ground for new physics searches. Contributions dueto virtual particles in the loop allow one to probe, at relatively low energies, new physicsat large mass scales. We search for the rare FCNC process B+ → K+ [tau]+[tau]− using datacollected by the BABAR detector at the SLAC National Accelerator Laboratory. The BABARdata sample corresponds to a total integrated luminosity, at the energy of the [UPSILON](4S) reso-nance, of 424.4 fb−1 and 471 million BB pairs. For this search, hadronic Btag reconstructionis employed, where one B is exclusively reconstructed via one of many possible hadronicmodes. The remaining decay products in an event are then attributed to the signal B, onwhich the search for B+ → K+ [tau]+[tau]− is performed. Each [tau] is required to decay leptonically,into either an electron or a muon and the lepton neutrinos. Furthermore, a multi-variateanalysis technique (neural network) is used to select for signal events and suppress dominantbackground modes. No significant signal is observed. The resulting branching fraction ismeasured to be B(B+ → K+[tau]+[tau]−) = 1.310.66 (stat.)+0.35(sys.) × 10−3, which is consistent −0.61 −0.25with zero at the 1.9[sigma] level, with an upper limit of 2.25 ×10−3 at the 90% confidence level." --