123787607
The Contribution of Reggeon in charge exchange processes
We discuss in this paper The experimental results on maximum psedo-rapidity $\eta_{max}$ distribution in the charge exchange process $e+p\to e+n+X$ in ZEUS Collaboration at HERA. We calculate the contributions of \regg ($\rho$-Reggeon associated with $\rho$ meson) from regge phenomenology and $\pi^{+}$-exchange from pion cloud model. The results show that neither the \regg-exchange nor the pion cloud model alone can explain the experimental data well, but after considering both these two processes together, by using Monte Carlo simulation, a good agreement between theoretical results and experimental data is found. This means that in discussing the large rapidity gap phenomena in deep inelastic scattering, both of the two processes play substantial role.
120706629
Contribution of Reggeon in Charge Exchange Processes of Deep Inelastic Scattering
The experimental results on maximum pseudo-rapidity ηmax distribution in the charge exchange processes e + P → e + N + X(X means anything) are discussed. The contributions of reggeon from Regge phenomenology and of π+-exchange from pion cloud model are calculated. The results show that neither the Rρ-exchange nor the pion cloud model alone can explain the experimental data well, but after considering these two processes together, by using Monte Carlo simulation, a good agreement between the theoretical results and experimental data is found.
204003965
Textures and hierarchies in quark mass matrices with four texture-zeros
A systematic analysis on the phenomenologically allowed textures in Hermitian quark mass matrices with four texture-zeros is presented. The current data allow a full determination of the mass matrix elements, provided that the actual number of the parameters in the matrices is less than or equal to ten. Besides the standard texture with zeros located in (1,1) and (1,3) positions, we find four new type of parallel mass matrices. All of them are found to have similar hierarchical structures: three of the nonzero matrix elements are at the same order of magnitude with a small geometric hierarchy, while the remaining one is relatively much smaller. These textures show a possibility that a realistic quark mass matrix may have an approximate flavor $S(2)_{L}\otimes S(2)_{R}$ symmetry, i.e. a partial flavor democracy. The absolute values of the CP violating phases in the matrix elements are found to be either close to their maximum ($\approx 90^\circ$) or very small ($\leq 10^{\circ}$). We also find twenty-six quasi-parallel and seventeen non-parallel textures allowed by the experimental data.
121392994
DARK MATTER CANDIDATES IN LEFT-RIGHT SYMMETRIC MODELS
We discuss an extended left-right symmetric model in which the decay of DM particle is induced by tiny soft charge-conjugation violating interactions, and calculate the spectra for cosmic-ray positrons, neutrinos and gamma-rays. The DM signals in the flux of high energy neutrinos can be significantly enhanced, as the triplets couple to both charged leptons and neutrinos. The predicted neutrino-induced muon flux can be several times larger than the case in which DM particle only directly decays into charged leptons. In addition, the charged components of the triplet give extra contributions to the high energy gamma-rays through internal bremsstrahlung process.
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.
118388670
Generic framework for anisotropic flow analyses with multiparticle azimuthal correlations
We present a new generic framework which enables exact and fast evaluation of all multi-particle azimuthal correlations. The framework can be readily used along with a correction framework for systematic biases in anisotropic flow analyses due to various detector inefficiencies. A new recursive algorithm has been developed for higher order correlators for the cases where their direct implementation is not feasible. We propose and discuss new azimuthal observables for anisotropic flow analyses which can be measured for the first time with our new framework. Effects of finite detector granularity on multi-particle correlations are quantified and discussed in detail. We point out the existence of a systematic bias in traditional differential flow analyses which stems solely from the applied selection criteria on particles used in the analyses, and is also present in the ideal case when only flow correlations are present. Finally, we extend the applicability of our generic framework to the case of differential multi-particle correlations.
771773
High spin baryon in hot strongly coupled plasma
We consider a strings-junction holographic model of a probe baryon in the finite-temperature supersymmetric Yang-Mills dual of the AdS-Schwarzschild black hole background. In particular, we investigate the screening length for a high spin baryon composed of rotating N-c heavy quarks. To rotate quarks by finite force, we put a hard infrared cutoff in the bulk and give quarks a finite mass. We find that N-c microscopic strings are embedded reasonably in the bulk geometry when they have finite angular velocity omega, similar to the meson case. By defining the screening length as the critical separation of quarks, we compute the omega dependence of the baryon screening length numerically and obtain a reasonable result which shows that baryons with high spin dissociate more easily. Finally, we discuss the relation between J and E-2 for baryons.
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.
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.
119221494
Neutrino masses and flavor mixing in a generalized inverse seesaw model with a universal two-zero texture
A generalized inverse seesaw model, in which the 9 x 9 neutrino mass matrix has vanishing (1,1) and (1,3) submatrices, is proposed. This is similar to the universal two-zero texture which gives vanishing (1,1) and (1,3) elements of the 3 x 3 mass matrices in both the charged lepton and neutrino sectors. We consider the Z(6) x Z(6) group to realize such texture zeros in the framework of the generalized inverse seesaw model. We also analyze the universal two-zero texture in the general case and propose two Ansatze to reduce the number of free parameters. Taking account of the new result of theta(13) from the Daya Bay experiment, we constrain the parameter space of the universal two-zero texture in the general case and in the two Ansatze, respectively. We find that one of the Ansatze works well.