Download or read book Search for the Higgs Boson Decaying to Two Tau Leptons in Proton antiproton Collisions at a Center of Mass Energy of 1 96 TeV written by Andrey Elagin and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the Higgs boson decaying to tau tau using 7.8 fb^-1 of pp collisions at 1.96 TeV collected with CDF II detector is presented. The search is sensitive to four production mechanisms of the Higgs boson: ggH, WH, ZH and VBF. Modes where one tau decay leptonically, and another decay, hadronically, are considered. Two novel techniques are developed and used in the search. A Probabilistic Particle Flow Algorithm is used for energy measurements of the hadronic tau candidates. The signal is discriminated from backgrounds by the Missing Mass Calculator, which allows for full invariant mass reconstruction of tau tau pair. The data are found to be consistent with the background only hypothesis. Therefore a 95% confidence level upper limit on the Standard Model Higgs boson cross section was set. At M_H=120 GeV/c^2 observed limit is 14.9 x sigma_SM x Br(H -> tau tau).
Download or read book Search for the Higgs Boson Decaying to Two Tau Leptons in p bar p Collisions at a Center of Mass Energy of 1 96 Tev written by and published by . This book was released on 2011 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the Higgs boson decaying to $ au au$ using 7.8f̃b${̂-1}$ of $par{p}$ collisions at 1.96T̃eV collected with CDF II detector is presented. The search is sensitive to four production mechanisms of the Higgs boson: ggH, WH, ZH and VBF. Modes where one tau decay leptonically, and another decay, hadronically, are considered. Two novel techniques are developed and used in the search. A Probabilistic Particle Flow Algorithm is used for energy measurements of the hadronic tau candidates. The signal is discriminated from backgrounds by the Missing Mass Calculator, which allows for full invariant mass reconstruction of $ au au$ pair. The data are found to be consistent with the background only hypothesis. Therefore a 95% confidence level upper limit on the Standard Model Higgs boson cross section was set. At $M_H$$=$120G̃eV/$c2̂$ observed limit is 14.9$ imessigma_{SM} imes Br (H → ??)$.
Download or read book Search for Lepton flavour violating H 2 mu tau Decays of the Higgs Boson with the ATLAS Detector written by and published by . This book was released on 2015 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: A direct search for lepton-flavour-violating H → [mu][tau] decays of the recently discovered Higgs boson with the ATLAS detector at the LHC is presented. The analysis is performed in the H → [mu][tau] had channel, where [tau] had is a hadronically decaying [tau] -lepton. The search is based on the data sample of proton-proton collisions collected by the ATLAS experiment corresponding to an integrated luminosity of 20.3 fb-1 at a centre-of-mass energy of √s = 8 TeV. No statistically significant excess of data over the predicted background is observed. As a result, the observed (expected) 95% confidence-level upper limit on the branching fraction, Br( H → [mu][tau] ), is 1.85% (1.24%).
Download or read book Search for a Neutral Higgs Boson Decaying to Tau Leptons Using CMS at the LHC written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a search for the standard model Higgs boson decaying to a [tau tau] pair using CMS data recorded at the LHC with 7 TeV and 8 TeV center of mass energy during 2011 and 2012 respectively. The search is performed using two channels [tau mu tau eta] and [tau epsilon tau eta] where [tau epsilon, tau mu] represent a [tau] decay to an electron or muon and [tau eta] represents a [tau] decay to hadron(s). The search is performed in the range 100 GeV
Download or read book Search for New Physics in Electron tau Final States in Proton Antiproton Collisions at 1 96 TeV written by Carsten Noeding and published by . This book was released on 2006 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the last decades, particle physicists have studied the tiniest building blocks of matter--the quarks and the leptons--and the forces between them in great detail. From these experiments, a theoretical framework has been built that describes the observed results with high precision. The achievement of this theory, which is referred to as the Standard Model of elementary particle physics, was the elaboration of a unified description of the strong, weak and electromagnetic forces in the framework of quantum gauge-field theories. Moreover, the Standard Model combines the weak and electromagnetic forces in a single electroweak gauge theory. The fourth force which is realized in nature, gravity, is too weak to be observable in laboratory experiments carried out in high-energy particle physics and is not part of the Standard Model. Although the Standard Model has proven highly successful in correlating a huge amount of experimental results, a key ingredient is as yet untested: the origin of electroweak symmetry breaking. Currently, the only viable ansatz that is compatible with observation is the Higgs mechanism. It predicts the existence of a scalar particle, called the Higgs boson, and the couplings to the fundamental Standard Model particles, however not its mass. An upper limit on the mass of the Higgs boson of {approx} 1 TeV can be inferred from unitarity arguments. One of the key tasks of particle physics in the next years will be to verify the existence of this particle. The introduction of an elementary scalar particle in a quantum field theory is highly problematic. The Higgs boson mass is subject to large quantum corrections, which makes it difficult to understand how its mass can be less than a TeV as required by theory. In addition, the Standard Model does not provide an answer to fundamental questions like the values of free parameters of the model, the pending integration of gravity or the evolution of the coupling constants of the fundamental forces at large energy regimes. Hence there are strong reasons to believe that the Standard Model is only a low-energy approximation to a more fundamental theory. One of the best studied candidates for an extension of the Standard Model is supersymmetry, which predicts the existence of a supersymmetric partner for each fundamental particle that differs only in spin. To allow different masses for Standard Model particles and their corresponding supersymmetric partners, supersymmetry must be broken. The mechanism behind supersymmetry breaking is currently unknown, however, various hypotheses exist. Supersymmetric models do not only solve the problem of the large quantum corrections to the Higgs boson mass, but they also allow the unification of the coupling constants at a common scale. In addition, certain supersymmetric models provide a suitable candidate for cold dark matter, which represents a large fraction of mass in our universe. Searches for supersymmetric particles have been performed by the four LEP experiments (ALEPH, DELPHI, L3, OPAL) up to the kinematic limit. Since no evidence for supersymmetric particles has been found, lower limits on their masses have been derived. The search for supersymmetry is now continuing at the Tevatron collider, located at the Fermi National Accelerator Laboratory in Batavia, Illinois. Two dedicated detector systems, CDF and D0, are installed at the Tevatron to analyze proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. A particular promising discovery channel for supersymmetry within the Tevatron energy range is the trilepton channel. In this channel, the lighter supersymmetric partners of the Higgs and gauge bosons, the charginos and neutralinos, decay into final states with leptons or hadrons and missing energy. Using the leptonic final states, the signal can be separated from the large Standard Model background. Supersymmetry requires an extension of the Standard Model Higgs sector, leading to more than one neutral Higgs boson. Enhanced couplings result in sizable cross sections for Higgs boson production, and the decay into a tau pair becomes an important Higgs boson discovery channel. Within the present thesis, a search for new physics predicted by constrained supersymmetric models is performed in final states consisting of an electron and a tau using data collected with the D0 detector from April 2002 to July 2004. The first analysis searches for the associated production of the lightest chargino and the second lightest neutralino in final states with an electron, a hadronically decaying tau, an additional lepton and missing transverse energy: e + {tau}{sub h} + {ell} + E{sub T}. The second analysis searches for neutral supersymmetric Higgs bosons in the decay mode {phi} {yields} {tau}{tau} {yields} e + {tau}{sub h} + E{sub T}. To improve the sensitivity, the results are interpreted in combination with other channels.
Download or read book High Energy Physics Index written by and published by . This book was released on 1990 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for a Higgs Boson Decaying Into gamma gamma to ell ell gamma with Low Dilepton Mass in Pp Collisions at sqrt s written by and published by . This book was released on 2015 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our search is described for a Higgs boson decaying into two photons, one of which has an internal conversion to a muon or an electron pair (ll?). The analysis is performed using proton–proton collision data recorded with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The events selected have an opposite-sign muon or electron pair and a high transverse momentum photon. No excess above background has been found in the three-body invariant mass range 120 mll? 150 GeV, and limits have been derived for the Higgs boson production cross section times branching fraction for the decay H → ?*? → ll?, where the dilepton invariant mass is less than 20 GeV. A Higgs boson with mH=125 GeV has a 95% confidence level (CL) exclusion observed (expected) limit is 6.7 (5.9sup+2.8/supsub-1.8/sub ) times the standard model prediction. Additionally, an upper limit at 95% CL on the branching fraction of H → (J/?)? for the 125 GeV Higgs boson is set at 1.5 × 10
Download or read book A Search for Displaced Leptons in the ATLAS Detector written by Lesya Horyn and published by Springer Nature. This book was released on 2022-02-07 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a search for long-lived particles decaying into displaced electrons and/or muons with large impact parameters. This signature provides unique sensitivity to the production of theoretical lepton-partners, sleptons. These particles are a feature of supersymmetric theories, which seek to address unanswered questions in nature. The signature searched for in this thesis is difficult to identify, and in fact, this is the first time it has been probed at the Large Hadron Collider (LHC). It covers a long-standing gap in coverage of possible new physics signatures. This thesis describes the special reconstruction and identification algorithms used to select leptons with large impact parameters and the details of the background estimation. The results are consistent with background, so limits on slepton masses and lifetimes in this model are calculated at 95% CL, drastically improving on the previous best limits from the Large Electron Positron Collider (LEP).
Download or read book Search for a Higgs Boson Decaying Into gamma gamma to ell ell gamma with Low Dilepton Mass in Pp Collisions at sqrt s written by and published by . This book was released on 2015 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our search is described for a Higgs boson decaying into two photons, one of which has an internal conversion to a muon or an electron pair (ll[gamma]). The analysis is performed using proton-proton collision data recorded with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The events selected have an opposite-sign muon or electron pair and a high transverse momentum photon. No excess above background has been found in the three-body invariant mass range 120
Download or read book A Search for Top Quark Decays to a Charged Higgs Boson in Proton antiproton Collisions at a Center of mass Energy of 1 8 TeV written by Brendan Bevensee and published by . This book was released on 1999 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book PEM 16 Entwicklung hersteller bergreifender Module f r den nutzerorientierten Einsatz der offenen Steuerungsarchitektur written by Gebrüder Heller and published by . This book was released on 1995 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for Lepton flavour violating Decays of the Higgs Boson written by and published by . This book was released on 2015 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first direct search for lepton-flavour-violating decays of the recently discovered Higgs boson (H) is described. The search is performed in the H 2![mu][tau]e and H2!mu][tau]h channels, where [tau]e and [tau]h are tau leptons reconstructed in the electronic and hadronic decay channels, respectively. The data sample used in this search was collected in pp collisions at a centre-of-mass energy of [arrow]" = 8 TeV with the CMS experiment at the CERN LHC and corresponds to an integrated luminosity of 19.7 fb−1. The sensitivity of the search is an order of magnitude better than the existing indirect limits. A slight excess of signal events with a significance of 2.4 standard deviations is observed. The p-value of this excess at MH=125 GeV is 0.010. The best fit branching fraction is [Beta](H 2![mu][tau])=(0.84+0.39-0.37)%. A constraint on the branching fraction, [Beta](H 2![mu][tau])
Download or read book Search for Lepton Flavour Violating Decays of the Higgs Boson to E Tau and E Mu in Proton proton Collisions at Sqrt s written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A direct search for lepton flavour violating decays of the Higgs boson (H) in the H to e tau and H to e mu channels is described. The data sample used in the search was collected in proton-proton collisions at sqrt(s)=8 TeV with the CMS detector at the LHC and corresponds to an integrated luminosity of 19.7 inverse femtobarns. No evidence is found for lepton flavour violating decays in either final state. Upper limits on the branching fractions, B(H to e tau)
Download or read book Search for an Exotic Decay of the Higgs Boson to a Pair of Light Pseudoscalars in the Final State of Two Muons and Two tau Leptons in Proton proton Collisions at s written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Standard Theory of Particle Physics written by Luciano Maiani and published by World Scientific Publishing Company. This book was released on 2016-08-25 with total page 483 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book gives a quite complete and up-to-date picture of the Standard Theory with an historical perspective, with a collection of articles written by some of the protagonists of present particle physics. The theoretical developments are described together with the most up-to-date experimental tests, including the discovery of the Higgs Boson and the measurement of its mass as well as the most precise measurements of the top mass, giving the reader a complete description of our present understanding of particle physics.
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1996 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evidence for the 125 GeV Higgs Boson Decaying to a Pair of tau Leptons written by and published by . This book was released on 2014 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for a standard model Higgs boson decaying into a pair of tau leptons is performed using events recorded by the CMS experiment at the LHC in 2011 and 2012. The dataset corresponds to an integrated luminosity of 4.9 inverse femtobarns at a centre-of-mass energy of 7 TeV and 19.7 inverse femtobarns at 8 TeV. Each tau lepton decays hadronically or leptonically to an electron or a muon, leading to six different final states for the tau-lepton pair, all considered in this analysis. An excess of events is observed over the expected background contributions, with a local significance larger than 3 standard deviations for m[H] values between 115 and 130 GeV. The best fit of the observed H to tau tau signal cross section for m[H] = 125 GeV is 0.78 +- 0.27 times the standard model expectation. These observations constitute evidence for the 125 GeV Higgs boson decaying to a pair of tau leptons.
