9,105 research outputs found

    Discovering Technicolor at Hadron Colliders

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    Strategies are presented for discovering light, color-singlet technipions (pi_T) produced in association with a vector boson through s-channel technirho production, at the Tevatron and LHC. Signal and W+jets background were simulated including detector effects. Tagging of b-quarks from the pi_T -> bb decay is found to be important to reduce the W+jets background. Kinematic properties of signal and background events are significantly different and simple cuts can be used to further improve the signal to background ratio.Comment: 4 pages, 6 figures, LaTeX; to appear in the Proceedings of the 1996 DPF/DPB Summer Study (Snowmass 1996

    Estimation of SM backgrounds to SUSY search in the 1-lepton + jets + MET channel

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    The ATLAS Collaboration has reported the first results of the search for SUSY particles in 1-lepton + 3 jets + MET final states. An essential ingredient for these results is a reliable background estimation in the signal region, in particular of the ttbar, W+jets and QCD backgrounds. The estimation of these three backgrounds is explained in this paper. The ttbar and W+jets backgrounds are obtained from a background dominated control region and extrapolated to the signal region, whereas for the estimation of the QCD background a matrix method is used.Comment: Contribution to conference proceedings (46th Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Italy, 13 - 20 Mar 2011

    High multiplicity W+jets predictions at NLO

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    In these proceedings we present results from a recent calculation for the production of a W boson in conjunction with five jets at next-to-leading order in perturbative QCD. We also use results at lower multiplicities to extrapolate the cross section to the same process with six jets.Comment: 5 pages, Proceedings for the DIS2013 conferenc

    W+jets Matrix Elements and the Dipole Cascade

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    We extend the algorithm for matching fixed-order tree-level matrix element generators with the Dipole Cascade Model in Ariadne to apply to processes with incoming hadrons. We test the algoritm on for the process W+n jets at the Tevatron, and find that the results are fairly insensitive to the cutoff used to regularize the soft and collinear divergencies in the tree-level matrix elements. We also investigate a few observables to check the sensitivity to the matrix element correction

    Charge asymmetry in W + jets production at the LHC

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    The charge asymmetry in W + jets production at the LHC can serve to calibrate the presence of New Physics contributions. We study the ratio {\sigma}(W^+ + n jets)/{\sigma}(W^- + n jets) in the Standard Model for n <= 4, paying particular attention to the uncertainty in the prediction from higher-order perturbative corrections and uncertainties in parton distribution functions. We show that these uncertainties are generally of order a few percent, making the experimental measurement of the charge asymmetry ratio a particularly useful diagnostic tool for New Physics contributions.Comment: 13 pages, 7 figures. Reference added. Slightly modified tex

    Approaching a strong fourth family

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    A heavy fourth family is an example of new physics which is well defined and familiar in some respects, but which nevertheless has radical implications. In particular it eliminates a light Higgs description of electroweak symmetry breaking. We discuss an early signal for heavy quarks at the LHC in the form of an excess of "WW-jets", and as well show how WW-jets may be useful in the reconstruction of the heavy quark masses. We argue that fourth family quarks can be distinguished from vector-like quarks of a similar mass at roughly the same time that a same sign lepton signal becomes visible. Given the large mass of the fourth neutrino we describe how a picture for neutrino mass emerges in the absence of right-handed neutrinos, and how it suggests the existence of a remnant flavor gauge symmetry. Based on talk given at "Second Workshop on Beyond 3 Generation Standard Model -- New Fermions at the Crossroads of Tevatron and LHC", January 2010, Taipei Taiwan.Comment: 14 pages, 10 figures, references added and slight change

    V+jets production at the CMS

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    Measurements of Vector Boson production in association with jets are presented, using p-p collision data at sqrt{s} = 7 TeV. The measurements presented include Z + jets azimuthal correlations, event shapes, vector boson + jets differential cross section measurements, hard double-parton scattering using W + jets events and electroweak Z + forward - backward jet production.Comment: 7 pages, 11 figure

    Vector boson+jets as background to top-quark physics at Tevatron and LHC

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    I review here the latest measurements related to vector boson production in association with light or heavy flavor jets at the Tevatron and at the LHC. The methods to estimate the W+jets and Z+jets background in top-quark analyses are also presented.Comment: 6 pages, 8 figures, proceedings for the 5th International Workshop on Top Quark Physics (Top2012), Winchester, U

    Study of the ratio of W+jets to Z+jets in proton--proton collisions at sqrt(s) = 10~TeV with the CMS detector at the CERN LHC

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    We present a simulation study of the ratio of W\mathrm{W}~+~jets to Z\mathrm{Z}~+~jets in pp\mathrm{pp} collisions at s=10\sqrt{s}=10 TeV and demonstrate the feasibility of measurements of the ratio up to four inclusive jets with O\mathcal O(100) pb‚ąí1^{-1} of early CMS data at the LHC. These measurements allow early understanding of W\mathrm{W}~+~jets and Z\mathrm{Z}~+~jets production at the LHC, since several detector effects and theoretical uncertainties cancel out in the ratio. They also provide a means of implementing a data-driven normalization of the W¬†+\mathrm{W}~+~jets and Z¬†+¬†\mathrm{Z}~+~jets backgrounds to important Standard Model processes (e.g. top quark) and new physics searches
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