3,988 research outputs found

    Breaking Eight-fold Degeneracies in Neutrino CP Violation, Mixing, and Mass Hierarchy

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    We identify three independent two-fold parameter degeneracies (\delta, \theta_{13}), sgn(\delta m^2_{31}) and (\theta_{23}, \pi/2-\theta_{23}) inherent in the usual three-neutrino analysis of long-baseline neutrino experiments, which can lead to as much as an eight-fold degeneracy in the determination of the oscillation parameters. We discuss the implications these degeneracies have for detecting CP violation and present criteria for breaking them. A superbeam facility with a baseline at least as long as the distance between Fermilab and Homestake (1290 km) and a narrow band beam with energy tuned so that the measurements are performed at the first oscillation peak can resolve all the ambiguities other than the (\theta_{23}, \pi/2-\theta_{23}) ambiguity (which can be resolved at a neutrino factory) and a residual (\delta, \pi-\delta) ambiguity. However, whether or not CP violation occurs in the neutrino sector can be ascertained independently of the latter two ambiguities. The (\delta,\pi-\delta) ambiguity can be eliminated by performing a second measurement to which only the \cos\delta terms contribute. The hierarchy of mass eigenstates can be determined at other oscillation peaks only in the most optimistic conditions, making it necessary to use the first oscillation maximum. We show that the degeneracies may severely compromise the ability of the proposed SuperJHF-HyperKamiokande experiment to establish CP violation. In our calculations we use approximate analytic expressions for oscillation probabilitites that agree with numerical solutions with a realistic Earth density profile.Comment: Revtex (singlespaced), 35 pages, 15 postscript figures, uses psfig.st

    Hadronic Phases and Isospin Amplitudes in D(B)ππD(B) \to \pi \pi and D(B)KKˉD(B) \to K \bar K Decays

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    Hadronic phase in ππ\pi \pi and KKˉK \bar K channels are calculated a la Regge. At the D mass one finds δπππ/3\delta_{\pi \pi} \approx \pi/3 and δKKˉπ/6\delta_{K \bar K} \approx -\pi/6 in good agreement with the CLEO data while at the B mass these angles are predicted to be, respectively, 1111^\circ and 7-7^\circ. With the hadronic phase eiδKKˉe^{i \delta_{K \bar K}} taken into account, a quark diagram decomposition of the isospin invariant amplitudes in DKKˉD \to K \bar K decays fits the data provided the exchange diagram contribution is about 1/3 of the tree level one.Comment: 10pages,late

    Matter profile effect in neutrino factory

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    We point out that the matter profile effect --- the effect of matter density fluctuation on the baseline --- is very important to estimate the parameters in a neutrino factory with a very long baseline. To make it clear, we propose the method of the Fourier series expansion of the matter profile. By using this method, we can take account of both the matter profile effect and its ambiguity. For very long baseline experiment, such as L=7332km, in the analysis of the oscillation phenomena we need to introduce a new parameter a1 a_{1} --- the Fourier coefficient of the matter profile --- as a theoretical parameter to deal with the matter profile effects.Comment: 21 pages, 15 figure

    Final State Interaction Phases in BKπ B \to K \pi Decay Amplitudes

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    A simple Regge pole model for KπK\pi scattering explains the large eiδe^{i \delta} between isospin amplitudes which is observed at the D meson mass (δπ/2\delta \approx \pi/2). It predicts δ1420\delta \approx 14^{\circ}- 20^{\circ} at the B mass. Implications for (BKπB \to K \pi) decays and extensions of the model to other two-body decay channels are briefly discussed.Comment: 8pages,late

    Measuring Higgs boson couplings at the LHC

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    For an intermediate mass Higgs boson with SM-like couplings the LHC allows observation of a variety of decay channels in production by gluon fusion and weak boson fusion. Cross section ratios provide measurements of various ratios of Higgs couplings, with accuracies of order 15% for 100 fb^{-1} of data in each of the two LHC experiments. For Higgs masses above 120 GeV, minimal assumptions on the Higgs sector allow for an indirect measurement of the total Higgs boson width with an accuracy of 10 to 20%, and of the H-->WW partial width with an accuracy of about 10%.Comment: 25 pages, Revtex, 1 figur

    Supersymmetry with Grand Unification

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    Supersymmetry (SUSY) has many well known attractions, especially in the context of Grand Unified Theories (GUTs). SUSY stabilizes scalar mass corrections (the hierarchy problem), greatly reduces the number of free parameters, facilitates gauge coupling unification, and provides a plausible candidate for cosmological dark matter. In this conference report we survey some recent examples of progress in SUSY-GUT applications.Comment: Talk V. Barger at the Workshop on Physics at Current Accelerators and the Supercollider, Argonne, June 1993, 15 pages + 12 PS figures included (uuencoded), (correct author list in header) MAD/PH/78

    Effects of Universal Extra Dimensions on Higgs signals at LHC

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    A major focus at the Large Hadron Collider (LHC) will be Higgs boson studies and it would be an interesting prospect to simultaneously probe for physics beyond the Standard Model (SM) in the Higgs signals. In this work we show as to what extent, the effects of Universal Extra Dimension (UED) can be isolated at the LHC through the Higgs signals. By doing a detailed study of the different uncertainties involved in the measurement of the rates for the process pp --> h --> gamma gamma we estimate the extent to which these uncertainties can mask the effects of the contributions coming from UED.Comment: 13 pages, LateX, Title changed, text and figures modified. Version to appear in IJMP
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