908 research outputs found

    Possible energy-dependence of Theta_13 in neutrino oscillations

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    A simple three-flavor neutrino-oscillation model is discussed which has both nonzero mass differences and timelike Fermi-point splittings, together with a combined bi-maximal and trimaximal mixing pattern. One possible consequence would be new effects in \nu_{\mu} \to \nu_{e} oscillations, characterized by an energy-dependent effective mixing angle \Theta_{13}. Future experiments such as T2K and NOvA, and perhaps even the current MINOS experiment, could look for these effects.Comment: 15 pages with revtex4; title changed in journa

    Status of FNAL SciBooNE experiment

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    SciBooNE is a new experiment at FNAL which will make precision neutrino-nucleus cross section measurements in the one GeV region. These measurements are essential for the future neutrino oscillation experiments. We started data taking in the antineutrino mode on June 8, 2007, and collected 5.19 \times 10^{19} protons on target (POT) before the accelerator shutdown in August. The first data from SciBooNE are reported in this article.Comment: 3 pages, 3 figures. Proceedings of the 10th International Conference on Topics in Astroparticle and Underground Physics (TAUP) 2007, Sendai, Japan, September 11-15, 200

    Which long-baseline neutrino experiments are preferable?

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    We discuss the physics of superbeam upgrades, where we focus on T2KK, a NuMI beam line based experiment NOvA*, and a wide band beam (WBB) experiment independent of the NuMI beam line. For T2KK, we find that the Japan-Korea baseline helps resolve parameter degeneracies, but the improvement due to correlated systematics between the two detectors (using identical detectors) is only moderate. For an upgrade of NOvA with a liquid argon detector, we demonstrate that the Ash River site is preferred compared to alternatives, such as at the second oscillation maximum, and is the optimal site within the U.S. For a WBB experiment, we find that high proton energies and long decay tunnels are preferable. We compare water Cherenkov and liquid argon technologies, and find the break-even point in detector cost at about 4:1. In order to compare the physics potential of the different experimental configurations, we use the concept of exposure to normalize the performance. We find that experiments with WBBs are the best experimental concept. NOvA* could be competitive with sufficient luminosity. If sin22θ13\sin^2 2\theta_{13} > 0.01, a WBB experiment can perform better than a neutrino factory.Comment: 31 pages, 13 figures, 5 tables. Version to appear in PR

    Bi-large neutrino mixing and the Cabibbo angle

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    Recent measurements of the neutrino mixing angles cast doubt on the validity of the so-far popular tri-bimaximal mixing ansatz. We propose a parametrization for the neutrino mixing matrix where the reactor angle seeds the large solar and atmospheric mixing angles, equal to each other in first approximation. We suggest such bi-large mixing pattern as a model building standard, realized when the leading order value of the reactor angle equals the Cabibbo angle.Comment: 4 pages, 2 figs. v2: matches version appearing in Phys.Rev.D, rapid communication

    ArgoNeuT, a liquid argon time projection chamber in a low energy neutrino beam

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    ArgoNeuT (Argon Neutrino Test), a NSF/DOE project at Fermilab, is the first LArTPC to go in a low energy neutrino beam and just the second LArTPC to go in a neutrino beam ever. ArgoNeuT sits just upstream of the on-axis MINOS near detector in the NuMI beamline, about 1 km from the target station and 100 m underground. The detector features a 47X40X90 cm (169 L) active volume TPC with a fully contained recirculation and purification system. Among other physics, ArgoNeuT will measure the charged-current quasi-elastic (anti-) neutrino cross section on argon at an energy of ~3 GeV.Comment: 3 pages, 2 figures, to appear in the proceedings of the 11th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2009), Rome, Italy, 1-5 July 200

    Muon Spectra of Quasi-Elastic and 1-Pion Production Events in LBL Neutrino Oscillation Experiments

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    The muon energy spectra of the quasi-elastic and 1-pion production events in a LBL experiment, like K2K, are predicted to follow closely the neutrino energy spectrum, with downward shifts of the energy scale by /2M/2 M and (+MΔ2M2)/2M( + M_\Delta^2 - M^2)/2 M respectively. These predictions seem to agree with the observed muon spectra in the K2K nearby detector. The corresponding muon spectra in the far-away (SK) detector are predicted to show characteristic spectral distortions induced by νμ\nu_\mu oscillation. Comparison of the predicted spectral distortions with the observed muon spectra of the 1-Ring and 2-Ring muon events in the SK detector will help to determine the oscillation parameters. The results will be applicable to other LBL experiments as well.Comment: 13 pages. One figure and a few comments added, final version to appear in P

    Resolving parameter degeneracies in long-baseline experiments by atmospheric neutrino data

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    In this work we show that the physics reach of a long-baseline (LBL) neutrino oscillation experiment based on a superbeam and a megaton water Cherenkov detector can be significantly increased if the LBL data are combined with data from atmospheric neutrinos (ATM) provided by the same detector. ATM data are sensitive to the octant of θ23\theta_{23} and to the type of the neutrino mass hierarchy, mainly through three-flavor effects in e-like events. This allows to resolve the so-called θ23\theta_{23}- and sign(Δm312\Delta m^2_{31})-parameter degeneracies in LBL data. As a consequence it becomes possible to distinguish the normal from the inverted neutrino mass ordering at 2σ2\sigma CL from a combined LBL+ATM analysis if sin22θ130.02\sin^2 2\theta_{13} \gtrsim 0.02. The potential to identify the true values of sin22θ13\sin^2 2\theta_{13} and the CP-phase δcp\delta_{cp} is significantly increased through the lifting of the degeneracies. These claims are supported by a detailed simulation of the T2K (phase II) LBL experiment combined with a full three-flavor analysis of ATM data in the HyperKamiokande detector.Comment: 25 pages, 10 figure