538 research outputs found

    Residual Symmetries Applied to Neutrino Oscillations at NOν\nuA and T2K

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    The results previously obtained from the model-independent application of a generalized hidden horizontal Z2\mathbb{Z}_2 symmetry to the neutrino mass matrix are updated using the latest global fits for the neutrino oscillation parameters. The resulting prediction for the Dirac CPCP phase δD\delta_D is in agreement with recent results from T2K. The distribution for the Jarlskog invariant JνJ_\nu has become sharper and appears to be approaching a particular region. The approximate effects of matter on long baseline neutrino experiments are explored, and it is shown how the weak interactions between the neutrinos and the particles that make up the Earth can help to determine the mass hierarchy. A similar strategy is employed to show how NOν\nuA and T2K could determine the octant of θa(θ23)\theta_a (\equiv \theta_{23}). Finally, the exact effects of matter are obtained numerically in order to make comparisons with the form of the approximate solutions. From this analysis there emerges some interesting features of the effective mass eigenvalues.Comment: 9 pages, 1 table, 17 figure

    Neutrino Mass Squared Differences in the Exact Solution of a 3-3-1 Gauge Model without Exotic Electric Charges

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    The mass splittings for the Majorana neutrinos in the exact solution of a particular 3-3-1 gauge model are computed here in detail. Since both sin2θ130\sin^{2}\theta_{13}\simeq0 and the mass splittings ratio rΔ0.033r_{\Delta}\simeq0.033 are taken into account, the analytical calculations seem to predict an inverted mass hierarchy and a mixing matrix with a texture based on a very close approximation to the bi-maximal mixing. The resulting formulas for the mass squared differences can naturally accomodate the available data if the unique free parameter (aa) gets very small values (1015\sim10^{-15}). Consequently, the smallness of the parameter requires (according to our method) a large breaking scale 106107\sim10^{6}-10^{7} TeV in the model. Hence, the results concerning the neutrino mass splittings may lead to a more precise tuning in the exact solution of the 3-3-1 model of interest, being able - at the same time - to recover all the Standard Model phenomenology and predict the mass spectrum of the new gauge bosons Z,X,YZ^{\prime},X,Y in accordance with the actual data. The minimal absolute mass in the neutrino sector is also obtained - m00.0035m_{0}\simeq0.0035 eV - in the case of our suitable approximation for the bi-maxcimal mixing.Comment: 10 pages, no figure

    High energy photon-neutrino elastic scattering

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    The one-loop helicity amplitudes for the elastic scattering process γνγν\gamma\nu\to\gamma\nu in the Standard Model are computed at high center of mass energies. A general decomposition of the amplitudes is utilized to investigate the validity of some of the key features of our results. In the center of mass, where s=2ω\sqrt{s} = 2\omega, the cross section grows roughly as ω6\omega^6 to near the threshold for WW-boson production, s=mW\sqrt{s} = m_W. Although suppressed at low energies, we find that the elastic cross section exceeds the cross section for γνγγν\gamma\nu\to\gamma\gamma\nu when s>13\sqrt{s}>13 GeV. We demonstrate that the scattered photons are circularly polarized and the net value of the polarization is non-zero. Astrophysical implications of high energy photon-neutrino scattering are discussed.Comment: 9 pages, 7 figures, RevTeX

    Photon-neutrino interactions

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    The cross sections for the processes γνγγν\gamma \nu \to \gamma \gamma \nu and effective Lagrangian derived from the Standard model. These cross sections are shown to be much larger than the elastic cross section $\sigma(\gamma\nu implications are discussed

    The exact eigenstates of the neutrino mass matrix without CP-phase violation

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    In this paper we obtain the exact mass-eigenstates of the Majorana physical neutrinos. We start by taking into account a general 3×33\times3 mass matrix without any CP-phase violation. It is then diagonalized by exactly solving an appropriate set of equations. The solution supplies straightforwardly the mass eigenvalues depending on the diagonal entries and mixing angles. Finally, the consequences of these analytical expressions are discussed assuming various phenomenological restrictions such as conserving the global lepton number L=LeLμLτL=L_{e}-L_{\mu}-L_{\tau} and the μτ\mu-\tau interchange symmetry. The minimal absolute mass in the neutrino sector is also obtained since the two plausible scenarios invoked above are employed.Comment: 9 pages, no figure

    Dips in Partial Wave Amplitudes from Final State Interactions

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    We consider the dip-peak structures in the J=0 partial wave amplitudes for processes \gamma\gamma\rightarrow W^+W^-~ \mbox{and}~\gamma\gamma,gg\rightarrow t\overline{t} taking into account the corresponding Born term process and the rescattering process where the intermediate state is rescattered through the exchange of Higgs resonance state in the direct channel.Comment: 9 pages, CPP-93-21, 6 figures not include

    gamma nu -> gamma gamma nu and crossed processes at energies below m_W

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    The cross sections for the processes γνγγν\gamma \nu\to \gamma \gamma \nu, γγγννˉ\gamma\gamma\to\gamma\nu\bar{\nu} and ννˉγγγ\nu\bar{\nu}\to\gamma\gamma\gamma are calculated for a range of center of mass energies from below mem_e to considerably above mem_e, but much less than mWm_W. This enables us to treat the neutrino--electron coupling as a four--Fermi interaction and results in amplitudes which are electron box diagrams with three real photons and one virtual photon at their vertices. These calculations extend our previous low--energy effective interaction results to higher energies and enable us to determine where the effective theory is reliable.Comment: 12 pages, RevTex, 10 postscript figures include
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