177 research outputs found

    Precision Electroweak Parameters and the Higgs Mass

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    The status of various precisely measured electroweak parameters is reviewed. Natural relations among them are shown to constrain the Higgs mass, m_H, via quantum loop effects to relatively low values. A comparison with direct Higgs searches is made.Comment: To be published in the Proceedings of MuMu99-5th International Conference on Physics Potential and Development of Muon Colliders, San Francisco, CA, Dec. (1999). 12 pages, Late

    Intense Neutrino Beams and Leptonic CP Violation

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    Effects of the Leptonic CP violating phase,\delta, on 3 generation neutrino oscillation rates and asymmetries are discussed. A figure of merit argument is used to show that our ability to measure the phase \delta is rather insensitive to the value of \theta_{13} (for \sin^22\theta_{13}\gsim0.01) as well as the detector distance (for very long oscillation baselines). Using a study of \nu_\mu\to\nu_e oscillations for BNL-Homestake (2540 km) we show that a conventional horn focused wide band neutrino beam generated by an intense 1-2 MW proton source combined with a very large water Cherenkov detector (250-500 kton) should be able to determine \delta to about \pm 15^\circin5×107secofrunning.Inaddition,suchaneffortwouldalsomeasuretheotheroscillationparameters(θij,Δmij2)withhighprecision.SimilarfindingsapplytoaFermilabHomestake(1280km)baseline.WealsobrieflydiscussfeaturesofSuperbeams,NeutrinoFactoriesandBetaBeams.Comment:7pages, in 5\times 10^7sec of running. In addition, such an effort would also measure the other oscillation parameters (\theta_{ij},\Delta m^2_{ij}) with high precision. Similar findings apply to a Fermilab-Homestake (1280 km)baseline. We also briefly discuss features of Superbeams, Neutrino Factories and Beta-Beams.Comment: 7 pages, Figures, to be published in Neutrino2006 Proceeding

    Improved Calculation of Electroweak Radiative Corrections and the Value of V_ud

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    A new method for computing hadronic effects on electroweak radiative corrections to low-energy weak interaction semileptonic processes is described. It employs high order perturbative QCD results originally derived for the Bjorken sum rule along with a large N QCD-motivated interpolating function that matches long and short-distance loop contributions. Applying this approach to the extraction of the CKM matrix element V_ud from superallowed nuclear beta decays reduces the theoretical loop uncertainty by about a factor of 2 and gives V_ud = 0.97377(11)(15)(19). Implications for CKM unitarity are briefly discussed.Comment: 12 pages, no figures. Ref. [8] correcte