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Our search for compositeness of electrons and muons is presented using a data sample of proton-proton collisions at a center-of-mass energy of √(s) = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb-1. Excited leptons (l*) produced via contact interactions in conjunction with a standard model lepton are considered, and a search is made for their gauge decay modes. The decays considered are l* →l? and l* → lZ, which give final states of two leptons and a photon or, depending on the Z-boson decay mode, four leptons or two leptons and two jets. The number of events observed in data is consistent with the standard model prediction. Exclusion limits are set on the excited lepton mass, and the compositeness scale L. For the case Ml* = L the existence of excited electrons (muons) is excluded up to masses of 2.45 (2.47) TeV at 95% confidence level. The neutral current decays of excited leptons are considered for the first time, and limits are extended to include the possibility that the weight factors f and f ', which determine the couplings between standard model leptons and excited leptons via gauge mediated interactions, have opposite sign.
A search for excited leptons is carried out with the CMS detector at the LHC, using 36 inverse picobarns of pp collision data recorded at sqrt(s) = 7 TeV. The search is performed for associated production of a lepton and an oppositely charged excited lepton pp to l l*, followed by the decay l* to l gamma, resulting in the l l gamma final state, where l = electron or muon. No excess of events above the standard model expectation is observed. Interpreting the findings in the context of l* production through four-fermion contact interactions and subsequent decay via electroweak processes, first upper limits are reported for l* production at this collision energy. The exclusion region in the compositeness scale Lambda and excited lepton mass M(l*) parameter space is extended beyond previously established limits. For Lambda = M(l*), excited lepton masses are excluded below 1070 GeV/c2̂ for e* and 1090 GeV/c2̂ for mu* at the 95% confidence level.
Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
The 1997 International Europhysics Conference on High Energy Physics was held at the campus of the Hebrew University of Jerusalem and at the Jerusalem Renaissance Hotel, from August 19th to August 25th, 1997. This was the first time that the European Physical Society had its High Energy Physics Conference outside the boundary of Europe. A total of 550 physicists participated in the conference with a total of 250 presentations in the parallel sessions and 26 presentations in the plenary sessions. The Board of the of the High Energy and Particle Physics division (HEPP) of the EPS acted as the Scientific Organizing Committee. The Board acknowl edges the help of the International Advisory Committee as well as that of the Local Organizing Committee. The conference was co-organized by the Hebrew University of Jerusalem and by the Weizmann Institute of Science, with important help by physi cists from the Israeli Institute of Technology (Technion) and the Tel Aviv University.
The Eloisatron Project aims at the study of physics phenomena in hadron-hadron colliders at the limits of maximum energy and luminosity. QCD processes involving multiparticle final states have shown 'universality features' in different production reactions once the 'leading effects' are correctly accounted for. The study of these phenomena has three components: (i) at now-available energies; (ii) at future energies in the years to come; (iii) at extreme energies. The link between these components can be achieved by QCD and its developments.This volume reviews the recent status of QCD and discusses novel aspects of perturbative and non-perturbative approaches to different kinds of interactions. It contains various contributions on multihadron production (theory and phenomenology), perturbative QCD and pomeron physics. Also, the latest experimental results on pp, ep and e⁺e⁻ interactions are presented.
Production cross sections of excited leptons in ee− annihilation experiments are estimated. Light excited states can be produced below the characteristic energy scale at which hypothetical constituents of leptons become bound: therefore the estimates are expected to be valid for E/sub cm/ less than or equal to 100 GeV, and to a large degree, model independent. The results are expressed in terms of measurable low energy parameters. It is concluded that high precision experiments are needed for an effective search for excited leptons.