120104764
Limits on the Neutrino Magnetic Moment Using Super-Kamiokande Solar Neutrino Data
Existence of non-zero neutrino magnetic moment would mean new physics beyond the standard model. A search for the neutrino magnetic moment has been conducted using the high statistic solar neutrino data from Super-Kamiokande-I. This is done by looking for the distortion to the observed energy spectrum of recoil electrons. A non-zero neutrino magnetic moment would cause an increase of event rates at lower energies. The search found no clear signal of neutrino magnetic moment. A limit on the neutrino magnetic moment has been obtained at 3.6 × 10-10μB at 90% C.L. by fitting to the Super-Kamiokande day-night spectra. The effects of neutrino oscillation have been included in the analysis. Including results from other neutrino experiments limiting the oscillation region, a limit of 1.1 × 10-10μB at 90% C.L. was obtained.
118478816
Dependence of Neutrino Mixing Angles and CP-violating Phase on Mixing Matrix Parametrizations
We consider various neutrino mixing matrix parametrizations and the dependence of the mixing angles and CP-violating phase on the different parametrizations. The transformations of neutrino mixing parameters between various parametrizations are presented. Although the $\theta_{13}$ mixing angle is determined to be small in the conventional parametrization, we note that in several other parametrizations the values of $\theta_{13}$ are quite large. Should the value of $\theta_{13}$ turn out to be tiny in the conventional parametrization, this study suggests that other alternative mixing matrix representations would be more suitable for dertermining the value of the CP-violating phase.
122731978
Search for Non-zero Neutrino Magnetic Moments Using Super-Kamiokande-I Solar Neutrino Data
53612303
k-Inflation in noncommutative space–time
The power spectra of the scalar and tensor perturbations in the noncommutative k-inflation model are calculated in this paper. In this model, all the modes created when the stringy space–time uncertainty relation is satisfied, and they are generated inside the sound/Hubble horizon during inflation for the scalar/tensor perturbations. It turns out that a linear term describing the noncommutative space–time effect contributes to the power spectra of the scalar and tensor perturbations. Confronting the general noncommutative k-inflation model with latest results from Planck and BICEP2, and taking $$c_\mathrm{S}$$cS and $$\lambda $$λ as free parameters, we find that it is well consistent with observations. However, for the two specific models, i.e. the tachyon and DBI inflation models, it is found that the DBI model is not favored, while the tachyon model lies inside the $$1\sigma $$1σ contour, when the e-folding number is assumed to be around $$50\sim 60$$50∼60.
18834224
STATEFINDER DIAGNOSTIC FOR QUINTESSENCE WITH OR WITHOUT THERMAL INTERACTION
The cosmological dynamics of a minimally coupled scalar field that couples to the background matter with thermal interactions is investigated using statefinder diagnostics. The time evolution of the statefinder pairs {r, s} and {r, q} are obtained under the circumstance that different values of model parameters are chosen. We show that the thermal coupling term does not affect the location of the late-time attractor, but exerts an influence on the evolution of the statefinder parameters. The most notable feature of the r–s plane for the thermal coupling model, which is distinguished from the other dark energy models, is that some part of the curve with thermal coupling can form a closed loop in the second quadrant (r > 1, s < 0).
118992896
Quasinormal modes of stringy black holes
Abstract String theory is a promising candidate for a fundamental quantum theory of all interactions including Einstein gravity. Some solutions in string theory can be interpreted as black holes. Using the semi-analytic method and WKB method, the quasinormal modes (QNMs) of (1+1)-dimensional black hole in string theory are studied.The QNMs of (1+3)-dimensional black hole in string theory are also calculated through numerical approach.The numerical investigation has shown that the late time gravitational oscillation of the black hole under an external perturbation is dominated by certain QNMs.