4,738 research outputs found

    Anomalously interacting extra neutral bosons

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    We study phenomenological consequences of the Standard Model extension by the new spin-1 chiral fields with the internal quantum numbers of the electroweak Higgs doublets. There are at least three different classes of theories, all motivated by the hierarchy problem, which predict new vector weak-doublets with masses not far from the electro-weak scale. We discuss resonance production of these neutral chiral Z* bosons at hadron colliders. The bosons can be observed as a Breit-Wigner resonance peak in the invariant dilepton mass distributions in the same way as the well-known extra gauge Z' bosons. This includes them into a list of very interesting objects for early searches with the first LHC data. Moreover, the Z* bosons have unique signatures in transverse momentum, angular and pseudorapidity distributions of the final leptons, which allow to distinguish them from the other heavy neutral resonances.Comment: 8 pages, 9 figures, uses cimento.cls: for Proceedings of the 2010 Rencontres de Physique de la Vallee d'Aoste, La Thuil

    Search for gluinos with ATLAS at LHC

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    Prospects for ATLAS observation of a SUSY-like signal from two gluinos are investigated within a certain region of the mSUGRA parameter space, where the cross section of the two gluinos production via gluon-gluon fusion is estimated at a rather high level of 13 pb. The event selection trigger uses a very clear signature of the process (4 jets + 4 muons + up to 4 secondary vertices topology) when final decay products of each gluino are b-anti-b and muon-anti-muon pairs and the lightest SUSY particle, the neutralino. Rather high transverse missing energy carried away by two neutralinos is an essential signature of the event and also allows the relevant Standard Model background to be reduced significantly. The generation and reconstruction processes are performed by means of the ATLAS common software framework ATHENA.Comment: LaTeX, 9 pages, 7 eps figure

    A New Scintillator Tile/Fiber Preshower Detector for the CDF Central Calorimeter

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    A detector designed to measure early particle showers has been installed in front of the central CDF calorimeter at the Tevatron. This new preshower detector is based on scintillator tiles coupled to wavelength-shifting fibers read out by multi-anode photomultipliers and has a total of 3,072 readout channels. The replacement of the old gas detector was required due to an expected increase in instantaneous luminosity of the Tevatron collider in the next few years. Calorimeter coverage, jet energy resolution, and electron and photon identification are among the expected improvements. The final detector design, together with the R&D studies that led to the choice of scintillator and fiber, mechanical assembly, and quality control are presented. The detector was installed in the fall 2004 Tevatron shutdown and started collecting colliding beam data by the end of the same year. First measurements indicate a light yield of 12 photoelectrons/MIP, a more than two-fold increase over the design goals.Comment: 5 pages, 10 figures (changes are minor; this is the final version published in IEEE-Trans.Nucl.Sci.

    Study of TileCal Sampling Fraction for Improvement of Monte-Carlo Data Reconstruction

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    In this work we made a detailed calculation of Tile Calorimeter Sampling Fraction parameter (TSF) using single electron and pion Geant4 Monte-Carlo simulation of ATLAS hadronic calorimeter (TileCal) within ATHENA --- common software framework of ATLAS. Our study was based on MC Truth data provided by special Geant4 MC simulation objects --- Calibration Hits, design which was implemented in TileCal simulation by our group. We used this TSF value for reconstruction of TileCal single pions simulation data. It was done for ATLAS Combined test beam 2004 (CTB2004) configuration setup. Results of the reconstruction were compared with MC Truth and CTB2004 reconstructed experimental data. Good agreement between them shows quite evident improvement in TileCal MC data reconstruction of hadronic shower energy in electromagnetic scale