119286757
Dirac neutrinos with S"4 flavor symmetry in warped extra dimensions
We present a warped extra dimension model with the custodial symmetry SU(2)(L) x SU(2)(R) x U(1)(X) x P-LR based on the flavor symmetry S-4 X Z(2) x Z(2)', and the neutrinos are taken to be Dirac particles. At leading order, the democratic lepton mixing is derived exactly, and the high-dimensional operators introduce corrections of order lambda(c) to all the three lepton mixing angles such that agreement with the experimental data can be achieved. The neutrino mass spectrum is predicted to be of the inverted hierarchy and the second octant of theta(23) is preferred. We suggest the modified democratic mixing, which is obtained by permuting the second and the third rows of the democratic mixing matrix, should be a good first order approximation to understanding sizable theta(13) and the first octant of theta(23). The constraints on the model from the electroweak precision measurements are discussed. Furthermore, we investigate the lepton mixing patterns for all the possible residual symmetries G(nu) and G(l) in the neutrino and charged lepton sectors, respectively. (C) 2013 Elsevier B.V. All rights reserved.
119273408
Majorana CP-violating phases in neutrino-antineutrino oscillations and other lepton-number-violating processes
If the massive neutrinos are identified to be the Majorana particles via a convincing measurement of the neutrinoless double beta (0 nu beta beta) decay, how to determine the Majorana CP-violating phases in the 3 x 3 lepton flavor mixing matrix U will become a desirable experimental question. The answer to this question is to explore all the possible lepton-number-violating (LNV) processes in which the Majorana phases really matter. In this paper we carry out a systematic study of CP violation in neutrino-antineutrino oscillations, whose CP-conserving parts involve six independent 0 nu beta beta-like mass terms (alpha beta) and CP-violating parts are associated with nine independent Jarlskog-like parameters V-alpha beta(ij) (for alpha, beta = e, mu, tau and i, j = 1, 2, 3). With the help of current neutrino oscillation data, we analyze the sensitivities of vertical bar (alpha beta)vertical bar and V-alpha beta(ij) to the three CP-violating phases of U, and illustrate the salient features of six independent CP-violating asymmetries between nu(alpha) -> (nu) over bar (beta) and (nu) over bar (alpha) -> nu(beta) oscillations. As a by-product, the effects of the CP-violating phases on the LNV decays of doubly and singly charged Higgs bosons are reexamined by taking account of the unsuppressed value of theta(13). Such CP-conserving LNV processes can be complementary to the possible measurements of neutrino-antineutrino oscillations in the distant future.
117546416
Majorana phases in neutrino-antineutrino oscillations
If the massive neutrinos are Majorana particles, neutrinoless double beta ($0\nu\beta\beta$) decay experiments are not enough to determine the Majorana phases. We carry out a systematic study of CP violation in neutrino-antineutrino oscillations. In these processes, CP-conserving parts involve six independent $0\nu\beta\beta$-like mass terms $\langle m\rangle_{\alpha\beta}$ and CP-violating parts are associated with nine independent Jarlskog-like parameters ${\cal V}^{ij}_{\alpha\beta}$ (for $\alpha, \beta = e, \mu, \tau$ and $i, j = 1, 2,3$). With the help of current neutrino oscillation data, we illustrate the salient features of six independent CP-violating asymmetries between $\nu_\alpha \to \bar{\nu}_\beta$ and $\bar{\nu}_\alpha \to \nu_\beta$ oscillations.
118334948
Non-Hermitian perturbations to the Fritzsch textures of lepton and quark mass matrices
Abstract We show that non-Hermitian and nearest-neighbor-interacting perturbations to the Fritzsch textures of lepton and quark mass matrices can make both of them fit current experimental data very well. In particular, we obtain θ 23 ≃ 45 ° for the atmospheric neutrino mixing angle and predict θ 13 ≃ 3 ° to 6° for the smallest neutrino mixing angle when the perturbations in the lepton sector are at the 20% level. The same level of perturbations is required in the quark sector, where the Jarlskog invariant of CP violation is about 3.7 × 10 − 5 . In comparison, the strength of leptonic CP violation is possible to reach about 1.5 × 10 − 2 in neutrino oscillations.
118385106
Holographic RG flow and sound modes of sQGP
A bstractWe consider the hydrodynamics of strongly interacting quark gluon plasma in finite temperature and density using the holographic duality of charged black hole in anti DeSitter space. We calculate the transport coefficients at arbitrary energy scale by considering the holographic screen at finite radial position. We first calculate the flow of sound velocity in this method and check the consistence with previous result. Then we calculate diffusion constant of charge and find that Einstein relation between susceptibility, conductivity and diffusion constants will hold at arbitrary slice.
119123104
Mixing-induced CP violating sources for electroweak baryogenesis from a semiclassical approach
The effects of flavor mixing in electroweak baryogenesis is investigated in a generalized semiclassical WKB approach. Through calculating the non-adiabatic corrections to the particle currents, it is shown that extra CP violation sources arise from the off-diagonal part of the equation of motion of particles moving inside the bubble wall. This type of mixing-induced source is of first order in a derivative expansion of the Higgs condensate, but it is oscillation suppressed. The numerical importance of the mixing-induced source is discussed in the minimal supersymmetric standard model and compared with the source term induced by a semiclassical force. It is found that in a large parameter space where oscillation suppression is not strong enough, the mixing-induced source can dominate over that from the semiclassical force.
119292340
Enhancement of dark matter relic density from late time dark matter conversions
We demonstrate that if the dark matter (DM) in the Universe contains multiple components, the possible interactions between the DM components may convert the heavier DM components into lighter ones. It is then possible that the lightest DM component with an annihilation cross section significantly larger than that of the typical weakly interacting massive particle (WIMP) may lead to a relic density in agreement with cosmological observations, due to an enhancement of number density from the DM conversion process at late time after the thermal decoupling. This may provide an alternative source of boost factor relevant to the positron and electron excesses reported by the recent DM indirect search experiments.
118464754
Exploration of decaying dark matter in a left-right symmetric model
SU(2)(L) triplet scalars appear in models motivated for the left-right symmetry, neutrino masses, and dark matter (DM), etc. If the triplets are the main decay products of the DM particle, and carry nonzero lepton numbers, they may decay dominantly into lepton pairs, which can naturally explain the current experimental results reported by PAMELA and Fermi-LAT or ATIC. We discuss this possibility in an extended left-right symmetric model in which the decay of the DM particle is induced by tiny soft charge-conjugation (C) violating interactions, and calculate the spectra for cosmic-ray positrons, neutrinos, and gamma rays. We show that the DM signals in the flux of high energy neutrinos can be significantly enhanced, as the triplets couple to both charged leptons and neutrinos with the same strength. In this scenario, the predicted neutrino-induced muon flux can be several times larger than the case in which the DM particle only directly decays into charged leptons. In addition, the charged components of the triplet may give an extra contribution to the high energy gamma rays through an internal bremsstrahlung process, which depends on the mass hierarchy between the DM particle and the triplet scalars.
118983113
Separating Different Models from Measuring $\alpha, \beta, \gamma$
New physics effects on the $B^0-\bar{B}^0$ mixing and B-decay amplitudes are discussed. By a combined analysis, the model of new physics can be partially distinguished.It is emphasized that the extraction of unitarity angles $\beta$ and $\gamma$ through rare decay $K\to \pi\nu\tilde{\nu}$ and charged B decay $B^{\pm}\to DK^{\pm}$ respectively is not likely to be affected by new physics. Such an observation could be used to distinguish the new physics effects from different mode ls. For instance, the top quark two-Higgs doublet model can be easily separated from those models without new phase in B-decay amplitudes, and can be further distinguished from the most general two Higgs doublet model by its absence of new phase in the $B^0-\bar{B}^0$ mixing.