6,140 research outputs found

    Studies of Fragmentation and Colour Reconnection at LEP

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    Hadronic events at the Z pole have been investigated in search for Colour Reconnection effects and QCD coherence. Colour Reconnection effects are searched for in three-jet events and the data results are compared to the predictions of different Monte Carlo models. QCD colour coherence effects are tested through the multiplicity distributions of hadrons with restricted momenta, and the LEP1 e+e- data is compared to HERA e+p data under the equivalence assumption of the e+e- hemisphere with the current region of the Breit frame of reference.Comment: 4 pages, 4 figures, contribution to ICHEP06 proceeding

    Gauge Boson Self Couplings and four fermion final states at LEP

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    Four-fermion productions measured in the LEP2 data are reviewed. The total and differential cross-section yields represent the first clear evidence for the existence of gauge boson self couplings, in support of the non-abelian SU(2)xU(1) structure of the electroweak model, at the percent level.Comment: 4 pages, 3 figures. To appear in the Proceedings of 'XV IFAE - Incontri sulla Fisica delle Alte Energie', 23-26 April 2003, Lecce, Ital

    Four-fermion final states in e+e- collisions at LEP2

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    The measurements of four-fermion production rates performed at LEP2 in e+e- collisions at centre-of-mass energies ranging from 161 to 209 GeV are presented. The focus is put on processes that involve the production and decay of W or Z electroweak bosons. Results on W decay rates and couplings are also discussed.Comment: 5 pages, 3 figures. To appear in the Proceedings of 'XIV IFAE - Incontri sulla Fisica delle Alte Energie', 3-5 April 2002, Parm

    Measurements of the properties of the Higgs-like boson with the CMS experiment at the LHC

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    Measurements of the properties of the recently discovered Higgs-like boson are presented using data samples recorded by the CMS experiment corresponding to integrated luminosities of up to 5.1 fb−1 at 7TeV and up to 12.2 fb−1 at 8TeV in proton proton collisions at the LHC. The results combine decay modes in pairs of photons, Z bosons, W bosons, tau leptons and b quarks. The mass of the boson is determined to be 125.8 ± 0.4 (stat.) ± 0.4 (syst.)GeV, and the signal strength at the measured mass is μ = 0.88 ± 0.21, normalized to the standard model expectation. Combined results on couplings, spin and parity reveal a broad agreement with the expectations of a standard model Higgs boson

    Physics Behind Precision

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    This document provides a writeup of contributions to the FCC-ee mini-workshop on "Physics behind precision" held at CERN, on 2-3 February 2016.Comment: https://indico.cern.ch/event/469561

    Molecular Mimicry between Helicobacter pylori Antigens and H+,K+–Adenosine Triphosphatase in Human Gastric Autoimmunity

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    Autoimmune gastritis and Helicobacter pylori–associated gastric atrophy develop through similar mechanisms involving the proton pump H+,K+–adenosine triphosphatase as autoantigen. Here, we report that H. pylori–infected patients with gastric autoimmunity harbor in vivo–activated gastric CD4+ T cells that recognize both H+,K+–adenosine triphosphatase and H. pylori antigens. We characterized the submolecular specificity of such gastric T cells and identified cross-reactive epitopes from nine H. pylori proteins. Cross-reactive H. pylori peptides induced T cell proliferation and expression of T helper type 1 functions. We suggest that in genetically susceptible individuals, H. pylori infection can activate cross-reactive gastric T cells leading to gastric autoimmunity via molecular mimicry

    Search for CP Violation in the Decay Z -> b (b bar) g

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    About three million hadronic decays of the Z collected by ALEPH in the years 1991-1994 are used to search for anomalous CP violation beyond the Standard Model in the decay Z -> b \bar{b} g. The study is performed by analyzing angular correlations between the two quarks and the gluon in three-jet events and by measuring the differential two-jet rate. No signal of CP violation is found. For the combinations of anomalous CP violating couplings, h^b=h^AbgVb−h^VbgAb{\hat{h}}_b = {\hat{h}}_{Ab}g_{Vb}-{\hat{h}}_{Vb}g_{Ab} and hb∗=h^Vb2+h^Ab2h^{\ast}_b = \sqrt{\hat{h}_{Vb}^{2}+\hat{h}_{Ab}^{2}}, limits of \hat{h}_b < 0.59and and h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st

    Dark matter searches at LHC

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    Besides Standard Model measurements and other Beyond Standard Model studies, the ATLAS and CMS experiments at the LHC will search for Supersymmetry, one of the most attractive explanation for dark matter. The SUSY discovery potential with early data is presented here together with some first results obtained with 2010 collision data at 7 TeV. Emphasis is placed on measurements and parameter determination that can be performed to disentangle the possible SUSY models and SUSY look-alike and the interpretation of a possible positive supersymmetric signal as an explanation of dark matter.Comment: 15 pages, 14 figures, Invited plenary talk given at DISCRETE 2010: Symposium On Prospects In The Physics Of Discrete Symmetries, 6-11 Dec 2010, Rome, Ital
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