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 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 Search for the Rare Decay of a B Meson to a K Meson and Two Neutrinos written by John Gregg Thayer and published by . This book was released on 2004 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Search for the Rare Decay B Meson to Two Photons written by Andrew Michael Ruland and published by . This book was released on 2010 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes a search for the rare radiative decay of a B meson to two photons. 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. The search for this rare decay was performed using the data collected with the BaBar detector at the SLAC National Accelerator Laboratory PEP-II storage ring operating at the Upsilon(4S) resonance. The analysis uses a dataset with an integrated luminosity of 425.7 fb-1 corresponding to 467 million BB pairs. A signal yield of 21.3 +12.8 -11.8 events with a significance of 1.88 sigma was measured using an unbinned extended maximum likelihood fit. An upper limit on the branching fraction is set at the 90% confidence level of less than 3.2 times 10^-7. This is about two times more stringent than the best upper limit of less than 6.2 times 10^-7 published by the Belle collaboration.
Download or read book Search for Semileptonic Decays in the B Meson Into the Lambda subscript C Baryon written by Tomohiko Tanabe and published by . This book was released on 2009 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 Rare B Decays in BABAR written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements and searches for rare B decays have been performed with the BaBar detector at the PEP-II e[sup +]e[sup -] asymmetric B Factory, operating at the [Upsilon](4S) resonance. The authors report some recent branching fraction measurements on hadronic and radiative B decays, occurring from b --> s/d and b --> u transitions. Most of the results presented here are based on a data sample corresponding to a luminosity of 81.9 fb[sup -1].
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 A Search for B Meson Decay to a Muon a Neutrino and a Photon written by Michael G. Greene and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Search for the Rare Decay of a Charged B Meson Into a Charged K Meson a Neutrino and an Anti neutrino written by Joachim Harnois-Déraps and published by . This book was released on 2006 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The document describes a search for the rare decay B[bar] [right arrow] K[bar]vv̄ in a data set of about 230 millions of BB[bar] pairs recorded by the BABAR detector at the PEP-II B Factory, via the process e+e- [right arrow] [Upsilon](4S) [right arrow] BB[bar]. The method used selects events in which the B+ meson is fully reconstructed, and looks for a K[bar] in the rest of the event. This is accomplished by applying kinematical and topological restrictions that select B[bar] [right arrow] K[bar]vv̄ events with the largest possible efficiency, while rejecting a maximum amount of background events. The number of background events is estimated from data and from simulated events, while the value of the selection efficiency relies solely on the simulation of B[bar] [right arrow] K[bar]vv̄ decays in the BABAR detector. These two numbers are required in order to set an upper limit on the branching ratio. We analyze a subset of the data sample and provide an interpretation of the result." --
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 Search for New Physics Using Radiative B Meson Decays and Lifetime Measurment of the B Meson with the Belle II Experiment written by Reem Rasheed and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: After the Big Bang matter and antimatter were present in equal amounts. Today, however, everything we see, is made almost entirely of matter. A fundamental ingredient to explain this asymmetry between matter and antimatter is the violation of the CP (Charge Parity) symmetry. CP violation has been observed but quantitatively not enough to explain the huge asymmetry. The Belle II experiment in Japan studies the particles produced in electron-positron collisions at the SuperKEKB collider, the highest intensity collider in the World, allowing a high precision measurements of the known sources of CP violation and looking for new ones. In my PhD, I worked on measuring the CP violation in B meson radiative decays (decays with photon in final state) particularly promising thanks to their high sensitivity to possible new processes. Following this analysis, I started a new measurement of the B mesons lifetime where I could verify the robustness of the tools used in the CP violation measurement.
Download or read book Rare B Decays from the CDF Experiment written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The high cross-section for the production of b quarks at the Tevatron hadron collider make it an ideal place to search for rare B meson species and very low branching fraction decay modes of the more common B mesons. This paper reports the recent discovery of the Bc meson by the CDF collaboration. It also discusses the observation of rare B meson final states involving?(2S) mesons and searches for ultra-rare decays such as B 2!??−
Download or read book B Meson Decays to Quasi Two Body Charmless Final States at BaBar written by A. Lazzaro and published by . This book was released on 2005 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present results for measurement of the decays to charmless final states of B{sup 0} meson to {eta}K{sup 0}, {eta}{omega}, a{sub 1}{sup +}(1260){pi}{sup -} with a{sub 1}{sup +}(1260) {yields} {pi}{sup +}{pi}{sup +}{pi}{sup -}, and of B{sup +} to {eta}{rho}{sup +}, {eta}{prime}{pi}{sup +}. Analyses are based on data taken with the BABAR detector at the PEP-II asymmetric e{sup +}e{sup -} collider at SLAC.
Download or read book Search for B Meson Decays to Two Body Final States with A0 980 Mesons written by and published by . This book was released on 2004 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present a search for B decays to charmless final states involving charged or neutral a0 mesons. The data sample corresponds to 89 million B{bar B} pairs collected with the BABAR detector operating at the PEP-II asymmetric-energy B Factory at SLAC. They find no significant signals and determine the following 90% C.L. upper limits: [Beta](B° 2!a0− [pi])
