2,687 research outputs found

    NLO Simulations of Chargino Production at the ILC

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    We present an extension of the Monte Carlo Event Generator Whizard which includes chargino production at the ILC at NLO. We present two ways of adding photonic contributions. We present results for cross sections and event generation.Comment: 4 pages, to appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 200

    Simplified Models for New Physics in Vector Boson Scattering - Input for Snowmass 2013

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    In this contribution to the Snowmass process 2013 (which is a preliminary version of [1]) we give a brief review of how new physics could enter in the electroweak (EW) sector of the Standard Model (SM). This new physics, if it is directly accessible at low energies, can be parameterized by explicit resonances having certain quantum numbers. The extreme case is the decoupling limit where those resonances are very heavy and leave only traces in the form of deviations in the SM couplings. Translations are given into higher-dimensional operators leading to such deviations. As long as such resonances are introduced without a UV-complete theory behind it, these models suffer from unitarity violation of perturbative scattering amplitudes. We show explicitly how theoretically sane descriptions could be achieved by using a unitarization prescription that allows a correct description of such a resonance without specifying a UV-complete model.Comment: A Snowmass White Paper, minor typos, one formula update

    WHIZARD 2.2 for Linear Colliders

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    We review the current status of the WHIZARD event generator. We discuss, in particular, recent improvements and features that are relevant for simulating the physics program at a future Linear Collider.Comment: Talk presented at the International Workshop on Future Linear Colliders (LCWS13), Tokyo, Japan, 11-15 November 201

    Automated NLO QCD Corrections with WHIZARD

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    We briefly discuss the current status of NLO QCD automation in the Monte Carlo event generator WHIZARD. The functionality is presented for the explicit study of off-shell top quark production with associated backgrounds at a lepton collider.Comment: 9 pages, 5 figures, to appear in the proceedings of the European Physical Society Conference on High Energy Physics 2015 (EPS-HEP 2015), Vienna, Austria, 22nd to 29th of July 201

    Matching NLO QCD Corrections in WHIZARD with the POWHEG scheme

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    Building on the new automatic subtraction of NLO amplitudes in WHIZARD, we present our implementation of the POWHEG scheme to match radiative corrections consistently with the parton shower. We apply this general framework to two linear collider processes, e+e− → ttˉe^+e^-\,\to\,t\bar{t} and e+e− → ttˉHe^+e^-\,\to\,t\bar{t}H.Comment: 7 pages, 4 figures, to appear in the proceedings of the European Physical Society Conference on High Energy Physics 2015 (EPS-HEP 2015), Vienna, Austria, 22nd to 29th of July 201

    QCD NLO with Powheg matching and top threshold matching in WHIZARD

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    We present the status of the automation of NLO processes within the event generator WHIZARD. The program provides an automated FKS subtraction and phase space integration over the FKS regions, while the (QCD) NLO matrix element is accessed via the Binoth Les Houches Interface from an externally linked one-loop program. Massless and massive test cases and validation are shown for several e+e- processes. Furthermore, we discuss work in progress and future plans. The second part covers the matching of the NRQCD prediction with NLL threshold resummation to the NLO continuum top pair production at lepton colliders. Both the S-wave and P-wave production of the top pair are taken into account in the resummation. The inclusion in WHIZARD allows to study more exclusive observables than just the total cross section and automatically accounts for important electroweak and relativistic corrections in the threshold region.Comment: 9 pages, 3 figures, Talk given at 12th International Symposium on Radiative Corrections (Radcor 2015) and LoopFest XIV (Radiative Corrections for the LHC and Future Colliders); v2: reference adde

    Probing the Noncommutative Standard Model at Hadron Colliders

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    We study collider signals for the noncommutative extension of the standard model using the Seiberg-Witten maps for SU(3)_C x SU(2)_L x U(1)_Y to first order in the noncommutativity parameters theta_munu. In particular, we investigate the ensitivity of Z-gamma-production at the Tevatron and the LHC to the components of theta_munu. We discuss the range of validity of this approximation and estimate exclusion limits from a Monte Carlo simulation.Comment: 18 pages LaTeX, 23 figures. Slightly expanded introduction and additional references. Accepted for publication in Physical Review
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