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[en] With the latest results of a large mixing angle θ13 for neutrinos by the T2K, MINOS and Double Chooz experiments, we find that the self-complementarity (SC) relations agree with the data in some angle-phase parametrizations of the lepton mixing matrix. There are three kinds of self-complementarity relations: (1) θi+θj=θk=45°; (2) θi+θj=θk; (3) θi+θj=45° (where i, j, k denote the mixing angles in the angle-phase parametrizations). We present a detailed study on the self-complementarity relations in nine different angle-phase parametrizations, and also examine the explicit expressions in reparametrization-invariant form, as well as their deviations from global fit. These self-complementarity relations may lead to new perspective on the mixing pattern of neutrinos.
[en] The authors present a high-statistics precision measurement of the weak mixing angle done at Fermilab experiment E770 using the ratio of neutral-current to charged-current neutino-nucleon deep inelastic scattering at the CCFR neutrino detector in the Fermilab quad-triplet neutrino beam
[en] We study the complementarity between quark and lepton mixing angles (QLC), the sum of an angle in quark mixing and the corresponding angle in lepton mixing is π/4. Experimentally in the standard PDG parametrization, two such relations exist approximately. These QLC relations are accidental which only manifest themselves in the PDG parametrization. We propose reparametrization invariant expressions for the complementarity relations in terms of the magnitude of the elements in the quark and lepton mixing matrices. In the exact QLC limit, it is found that |Vus/Vud|+|Ve2/Ve1|+|Vus/Vud||Ve2/Ve1|=1 and |Vcb/Vtb|+|Vμ3/Vτ3|+|Vcb/Vtb||Vμ3/Vτ3|=1. Expressions with deviations from exact complementarity are obtained. Implications of these relations are also discussed.
[en] Recently, three reactor neutrino experiments, Daya Bay, Double Chooz and RENO have directly measured the neutrino mixing angle θ13. In this Letter, another important oscillation parameter, effective Δm312 (=Δm-tilde312) is measured using baseline dependence of the reactor neutrino disappearance. A global fit is applied to publicly available data and Δm-tilde312=2.95−0.61+0.42×10−3 eV2, sin22θ13=0.099−0.012+0.016 are obtained by setting both parameters free. This result is complementary to Δm-tilde312 to be measured by spectrum shape analysis. The measured Δm-tilde312 is consistent with Δm-tilde322 measured by νμ disappearance in MINOS, T2K and atmospheric neutrino experiments within errors. The minimum χ2 is small, which means the results from the three reactor neutrino experiments are consistent with each other
[en] The most important point is the measurement of the last unknown mixing angle θ13 that quantifies the change of an electron neutrino into a tau neutrino. 3 experiments based on neutrinos released by nuclear reactors have agreed to a value of 9 degrees for θ13. Another important point is the anomaly in the measured flux of neutrinos issued from nuclear reactors or radioactive sources when compared to computed values. A thorough study through experimental results from various experiments in the past shows a systematic difference: the measured flux of neutrinos systematically underestimates expected values by 7 per cent. In other words 7% of neutrinos seem to disappear between the moment of their creation and their detection which may hint at an unknown nuclear process or at the existence of a new neutrino: a 'barren' neutrino that does not contribute to weak interactions. (A.C.)
[en] The NOvA experiment, using the existing NuMI beamline, is planned for construction at Ash River, Minnesota. The experiment will provide a measurement of, or strong limit on the neutrino mixing angle θ13, and for sufficiently strong mixing, establish the hierarchy of the neutrino masses
[en] The neutrino mixing angle θ13 is currently a high-priority topic in the field of neutrino physics, with three different reactor neutrino experiments under way, searching for neutrino oscillations induced by this angle. A description of the reactor experiments searching for a non-zero value of θ13 is given, together with a discussion of their sensitivity within the next few years.
[en] The measurement of the reactor angle by the Daya Bay and RENO experiments in 2012 has ruled out the tri-bimaximal paradigm. Adopting an S4 family symmetry, we propose direct models of the trimaximal type TM1 in which the tri-bimaximal Klein symmetry of the neutrino sector is broken to a residual Z2 symmetry. In such a scenario, the solar mixing angle is decreased compared to its tri-bimaximal value by about 1°, thus bringing it in excellent agreement with experimental observation. The atmospheric mixing angle, on the other hand, depends on the CP violating Dirac phase δ. Imposing CP conservation in the family symmetry limit, we show how to break the CP symmetry via flavon VEVs with well-defined complex phases, so that sizable deviations of the atmospheric angle from maximal mixing, consistent with the latest global fits, are produced
[en] There are experimentally determined two best-fit points for the atmospheric neutrino mixing angle θ23: sin2θ23=0.413 (case A) and sin2θ23=0.594 (case B). In the bipair neutrino mixing scheme, we predict sin2θ23=√(2)−1 (case 1) to be consistent with the case A and sin2θ23=2−√(2) (case 2) to be consistent with the case B. If the case B is realized in nature, the bipair neutrino mixing provides a unique neutrino model consistent with the observation sin2θ23=0.594. However, the reactor neutrino mixing angle θ13 is predicted to be sin2θ13=0, which is inconsistent with the observation. We propose a new modification scheme to yield sin2θ13≠0 utilizing the charged lepton contribution and study its effect on both of CP-violating Dirac and Majorana phases, which is numerically estimated. It is found that there appear striking differences between the case 1 and the case 2 in their phase structure