4,162 research outputs found

    Prospects for New Physics at the LHC

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    High-energy collisions at the LHC are now starting. The new physics agenda of the LHC is reviewed, with emphasis on the hunt for the Higgs boson (or whatever replaces it) and supersymmetry. In particular, the prospects for discovering new physics in the 2010-2011 run are discussed.Comment: 13 pages, 9 figures, Invited Talk at Conference in Honor of Murray Gell-Mann's 80th Birthday, on Quantum Mechanics, Elementary Particles, Quantum Cosmology and Complexity, Nanyang Executive Centre, NTU, Singapore, 24th-26th February 201

    MCFM for the Tevatron and the LHC

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    A summary is given of the current status of the next-to-leading order (NLO) parton-level integrator MCFM. Some details are given about the Higgs + 2-jet process and the production and decay of ttˉt \bar{t}, both of which have recently been added to the code. Using MCFM, comparisons between the Tevatron running at s=2\sqrt{s}=2~TeV and the LHC running at s=7\sqrt{s}=7~TeV are made for standard model process including the production of Higgs bosons. The case for running the Tevatron until 16fb−1^{-1} are accumulated by both detectors is sketched.Comment: Talk presented by R.K Ellis at Loops and Legs in Quantum Field Theory 2010, Woerlitz, Germany, April 25-30, 2010, (6 pages and 4 figures

    Improved techniques for thermomechanical testing in support of deformation modeling

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    The feasibility of generating precise thermomechanical deformation data to support constitutive model development was investigated. Here, the requirement is for experimental data that is free from anomalies caused by less than ideal equipment and procedures. A series of exploratory tests conducted on Hastelloy X showed that generally accepted techniques for strain controlled tests were lacking in at least three areas. Specifically, problems were encountered with specimen stability, thermal strain compensation, and temperature/mechanical strain phasing. The source of these difficulties was identified and improved thermomechanical testing techniques to correct them were developed. These goals were achieved by developing improved procedures for measuring and controlling thermal gradients and by designing a specimen specifically for thermomechanical testing. In addition, innovative control strategies were developed to correctly proportion and phase the thermal and mechanical components of strain. Subsequently, the improved techniques were used to generate deformation data for Hastelloy X over the temperature range, 200 to 1000 C

    QCD corrections to the hadronic production of a heavy quark pair and a W-boson including decay correlations

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    We perform an analytic calculation of the one-loop amplitude for the W-boson mediated process 0 \to d u-bar Q Q-bar l-bar l, retaining the mass for the quark Q. The momentum of each of the massive quarks is expressed as the sum of two massless momenta and the corresponding heavy quark spinor is expressed as a sum of two massless spinors. Using a special choice for the heavy quark spinors we obtain analytic expressions for the one-loop amplitudes which are amenable to fast numerical evaluation. The full next-to-leading order (NLO) calculation of hadron+hadron \to W(\to e nu) b b-bar with massive b-quarks is included in the program MCFM. A comparison is performed with previous published work.Comment: 45 pages, 17 figure

    Hadronic production of a Higgs boson and two jets at next-to-leading order

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    We perform an update of the next-to-leading order calculation of the rate for Higgs boson production in association with two jets. Our new calculation incorporates the full analytic result for the one-loop virtual amplitude. This new theoretical information allows us to construct a code including the decay of the Higgs boson without incurring a prohibitive penalty in computer running time. Results are presented for the Tevatron, where implications for the Higgs search are sketched, and also for a range of scenarios at the LHC.Comment: 16 pages, 4 figure

    Testing the standard model and beyond

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    This paper is based on lectures presented to mathematical physicists and attempts to provide an overview of the present status of the Standard Model, its experimental tests, phenomenological and experimental motivations for going beyond the Standard Model via supersymmetry and grand unification, and ways to test these ideas with particle accelerators.This paper is based on lectures presented to mathematical physicists and attempts to provide an overview of the present status of the Standard Model, its experimental tests, phenomenological and experimental motivations for going beyond the Standard Model via supersymmetry and grand unification, and ways to test these ideas with particle accelerators

    Particles and cosmology: learning from cosmic rays

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    The density budget of the Universe is reviewed, and then specific particle candidates for non-bayonic dark matter are introduced, with emphasis on the relevance of cosmic-ray physics. The sizes of the neutrino masses indicated by recent atmospheric and solar neutrino experiments may be too small to contribute much hot dark matter. My favoured candidate for the dominant cold dark matter is the lightest supersymmetric particle, which probably weighs between about 50 GeV and about 600 GeV. Strategies to search for it via cosmic rays due to annihilations in the halo, Sun and Earth, or via direct scattering experiments, are mentioned. Possible superheavy relic particles are also discussed, in particular metastable string- or M-theory cryptons, that may be responsible for the ultra-high-energy cosmic rays. Finally, it is speculated that a non-zero contribution to the cosmological vacuum energy might result from incomplete relaxation of the quantum-gravitational vacuum.The density budget of the Universe is reviewed, and then specific particle candidates for non-bayonic dark matter are introduced, with emphasis on the relevance of cosmic-ray physics. The sizes of the neutrino masses indicated by recent atmospheric and solar neutrino experiments may be too small to contribute much hot dark matter. My favoured candidate for the dominant cold dark matter is the lightest supersymmetric particle, which probably weighs between about 50 GeV and about 600 GeV. Strategies to search for it via cosmic rays due to annihilations in the halo, Sun and Earth, or via direct scattering experiments, are mentioned. Possible superheavy relic particles are also discussed, in particular metastable string- or M-theory cryptons, that may be responsible for the ultra-high-energy cosmic rays. Finally, it is speculated that a non-zero contribution to the cosmological vacuum energy might result from incomplete relaxation of the quantum-gravitational vacuum.The density budget of the Universe is reviewed, and then specific particle candidates for non-bayonic dark matter are introduced, with emphasis on the relevance of cosmic-ray physics. The sizes of the neutrino masses indicated by recent atmospheric and solar neutrino experiments may be too small to contribute much hot dark matter. My favored candidate for the dominant cold dark matter is the lightest supersymmetric particle, which probably weighs between about 50 GeV and about 600 GeV. Strategies to search for it via cosmic rays due to annihilations in the halo, Sun and Earth, or via direct scattering experiments, are mentioned. Possible superheavy relic particles are also discussed, in particular metastable string- or M-theory cryptons, that may be responsible for the ultra-high-energy cosmic rays. Finally, it is speculated that a non-zero contribution to the cosmological vacuum energy might result from incomplete relaxation of the quantum-gravitational vacuum

    Astroparticle physics: a personal outlook

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    At the request of the organizers, this talk surveys some of the hot topics discussed at this meeting, giving my {\it subjective views} on them. Subjects covered include the present age and Hubble expansion rate of the Universe - {\it inflation theorists need not yet abandon \Omega = 1}, theories of structure formation in the light of COBE and other data - {\it my favourite is a flat spectrum of initial perturbations subsequently amplified by mixed hot and cold dark matter}, neutrino masses and oscillations - {\it the only experimental indication I take seriously at the moment is the persistent solar neutrino deficit}, the lightest supersymmetric particle - {\it which may behave differently if conventional assumptions are relaxed}, and the axion - {\it much of the window between limits from SN 1987a and cosmology will be explored in an ongoing experiment}. Finally, I present a chronology of some possible interesting future experiments

    Single top production and decay at next-to-leading order

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    We present the results of a next-to-leading order analysis of single top production including the decay of the top quark. Radiative effects are included both in the production and decay stages, using a general subtraction method. This calculation gives a good treatment of the jet activity associated with single top production. We perform an analysis of the single top search at the Tevatron, including a consideration of the main backgrounds, many of which are also calculated at next-to-leading order.Comment: 35 pages + 15 figures, revtex
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