880 research outputs found

    Boson Fusion and Higgs production at the LHC in six fermion final states with one charged lepton pair

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    Boson boson scattering and Higgs production in boson boson fusion will be actively investigated at the LHC. We have performed a parton level study of all processes of the type q1q2→q3q4q5q6l+l−q_1 q_2 \to q_3 q_4 q_5 q_6 l^+l^- using for the first time a full fledged six fermion Monte Carlo event generator which employs exact matrix elements at \O(\alpha_{em}^6). We have examined Higgs production in vector boson fusion followed by the decay chain H→ZZ→l+l−jjH\to ZZ\to l^+l^-jj, including exactly all electroweak irreducible backgrounds. In the high mass region we have compared the case of a relatively light Higgs with the no-Higgs case. The integrated cross section for the latter case is more than twice that in the former for a minimum invariant mass of the ZVZV pair of about 800 \GeV. We find, in a preliminary anlysis at parton level that, summing up the muon and the electron channels, about 30 events are expected in the light Higgs case for L=100 fb−1fb^{-1}.Comment: Final version published in Phys.Rev.

    PHASE - An event generator for six fermion physics at the LHC

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    PHASE is a Monte Carlo event generator, under construction, for all Standard Model processes with six fermions in the final state at the LHC. It employs the full set of tree level Feynman diagrams, taking into account fermion masses for b quarks. The program can generate unweighted events for any subset of all six fermion final states in a single run, by making use of dedicated pre-samples. An interface to hadronization is provided.Comment: 4 pages, Latex, 1 figure. Talk given by E. Accomando at the IX International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT03), KEK, Tsukuba, December 1-5, 200

    Precision Measurements of the W-Boson Mass

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    The Standard Model of electroweak interactions has had great success in describing the observed data over the last three decades. The precision of experimental measurements affords tests of the Standard Model at the quantum loop level beyond leading order. Despite this great success it is important to continue confronting experimental measurements with the Standard Model predictions as any deviation would signal new physics. As a fundamental parameter of the Standard Model, the mass of the W-boson, M_W, is of particular importance. Aside from being an important test of the SM itself, a precision measurement of M_W can be used to constrain the mass of the Higgs boson, M_H. In this article we review the principal experimental techniques for determining M_W and discuss their combination into a single precision M_W measurement, which is then used to yield constraints on M_H. We conclude by briefly discussing future prospects for precision measurements of the W-boson mass.Comment: 37 pages, 13 figures, LaTex, to be published in volume 50 of Annual Review of Nuclear and Particle Scienc

    Exploring alternative symmetry breaking mechanisms at the LHC with 7, 8 and 10 TeV total energy

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    In view of the annnouncement that in 2012 the LHC will run at 8 TeV, we study the possibility of detecting signals of alternative mechanisms of ElectroWeak Symmetry Breaking, described phenomenologically by unitarized models, at energies lower than 14 TeV. A complete calculation with six fermions in the final state is performed using the PHANTOM event generator. Our results indicate that at 8 TeV some of the scenarios with TeV scale resonances are likely to be identified while models with no resonances or with very heavy ones will be inaccessible, unless the available luminosity will be much higher than expected
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