921 research outputs found

    Feasibility Studies of the Diffractive Bremsstrahlung Measurement at the LHC

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    Feasibility studies of an observation of the exclusive diffractive bremsstrahlung in proton-proton scattering at the LHC are reported. A simplified approach to the photon and the scattered proton energy reconstruction is used. The background influence is discussed.Comment: 15 pages, 6 figure

    Central exclusive production at RHIC

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    The present status and and future plans of the physics program of Central Exclusive Production at RHIC are described.Comment: 9 pages, 5 figures, to appear as a review article in IJMP

    On the mass relation of a meson nonet

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    It is pointed out that the omission of the effects of the transition between quarkonia or the assumption that the transition between quarkonia is flavor-independent would result in the inconsistent results for the pseudoscalar meson nonet. It is emphasized that the mass relation of the non-ideal mixing meson nonets should incorporate the effects of the flavor-dependent transition between quarkonia. The new mass relations of a meson nonet are presented.Comment: Latex, 10 pages, to appear in Mod. Phys. Lett.

    Search for Chargino and Neutralino Production at sqrt(s) = 192-209 GeV at LEP

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    Approximately 438 pb-1 of e+e- data from the OPAL detector, taken with the LEP collider running at centre-of-mass energies of 192-209 Gev, are analyzed to search for evidence of chargino pair production, e+e- -> tilde chi^+_1 tilde chi^-_1, or neutralino associated production, e+e- -> tilde chi^0_2 tilde chi^0_1. Limits are set at the 95% confidence level on the product of the cross-section for the process e+e- -> tilde chi^+_1 tilde chi^-_1 and its branching ratios to topologies containing jets and missing energy, of jest with a lepton and missing energy, and on the product of the cross-section for e+e- -> tilde chi^0_2 tilde chi^0_1 and its branching ratio to jets. R-parity conservation is assumed throughout this paper. When these results are interpreted in the context of the Constrained Minimal Supersymmetric Standard Model, limits are also set on the masses of the tilde chi^+-_1, tilde chi^0_1 and tilde chi^0_2, and regions of the parameter space of the model are ruled out. Nearly model-independent limits are also set at the 95% confidence level on sigma(e+e- -> tilde chi^+_1 tilde chi^-_1) with the assumption that each chargino decays via a W boson, and on sigma(e+e- -> tilde chi^0_2 tilde chi^0_1) with the tilde chi^0_2 assumed to decay via a Z^0.Comment: 33 pages, 13 figures, Submitted to Eur Phys J.

    QCD coherence in deep inelastic scattering at small x at HERA

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    QCD coherence effects in initial state radiation at small x in deep inelastic scattering in HERA kinematics are studied with the help of the Monte Carlo model SMALLX. Theoretical assumptions based on the CCFM evolution equation are reviewed and the basic properties of the partonic final states are investigated. The results are compared with those obtained in the conventional DGLAP evolution scheme.Comment: 23 pages, latex, 9 ps figures included. One reference added and citation in the paper improve

    How to Measure Chromo-magnetic Vacuum Background Field in e+ejetse^{+}e^{-}\to jets, Hadron-Hadron and Nucleus-Nucleus Collisions

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    We propose a new type of the measurement which is sensitive to the QCD vacuum color-magnetic fluctuations: A measure of the axial assymetry of the hadronic final states produced in the high energy e+ee^{+}e^{-} collisions is related to the chromomagnetic vacuum field strength.Comment: 11 pages,latex,no figures,replaced,final version which takes into account criticisms of referees of Phys.Rev. Title of the paper was changed. The formula (14) was corrected, notation in formulae (12) and (13) changed. Also we added forgotten vectorial notations,corrected misspellings and improved the style and gramma