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.
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.
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.
119249518
A TWO HIGGS BI-DOUBLET LEFT-RIGHT MODEL WITH SPONTANEOUS CP VIOLATION
We discuss a left-right symmetric model with two Higgs bi-doublet and spontaneous P and CP violation. The flavor changing neutral currents is suppressed by assuming approximate global U(1) family symmetry. We calculate the constraints from neural K meson mass difference ΔmK and demonstrate that a right-handed gauge boson W2 contribution in box-diagrams with mass around 600 GeV is allowed due to a negative interference with a light charged Higgs boson around 150 ~ 300 GeV. The W2 contribution to ɛK is suppressed from appropriate choice of additional CP phases appearing in the right-handed Cabbibo-Kobayashi-Maskawa(CKM) matrix. The model is found fully consistent with B0 mass difference and the mixing-induced CP asymmetry measurements.
118332759
Constraining Charming Penguins in Charmless B Decays
We discuss the correlations of charming penguin contributions to $B\to\pi\pi$, $\pi K$ and KK using approximate flavor SU(3) symmetry. Strong constraints are found from the direct CP asymmetries especially in $\pi K$ modes. We make a global fit to the latest data and find that only a small charming penguin is allowed, and the size of color-suppressed tree amplitude (C) relative to tree amplitudes (T) remains large $C/T\simeq0.6$, which disfavors the possibility of a large charming penguin as an explanation for the $\pi\pi$ puzzle. We show that a small charming penguin can still have sizable effect in the time-dependence CP asymmetries in KK mode.
41468370
Texture of Yukawa coupling matrices in general two Higgs doublet model
We discuss possible parallel textures of the Yukawa coupling matrices in the general two-Higgs doublet model (2HDM). In these textures the flavour changing neutral currents are naturally suppressed. Motivated by a phenomenologically successful texture with four texture zeros in the standard model, we propose a predictive ansatz for the Yukawa coupling matrices with the same texture in the general 2HDM. Compared with the six texture-zero-based ansatz proposed by Cheng and Sher, it is in better agreement with the data of quark mixings and CP violation. The four texture-zero-based ansatz predicts a different hierarchy in the Yukawa coupling matrix elements. As a consequence, in the lepton sector, the related Yukawa couplings are less constrained by the experimental upper bound of μ → eγ, which allows significantly larger predictions for other processes. The contributions from neutral scalar interactions to the lepton number violation decay modes l → l1l2l3 are calculated in both ansatz. It is shown that the predictions from the four texture-zero-based ansatz could be two orders of magnitude greater than that from the six texture-zero-based one. The branching ratio of μ → 3e and τ → 3μ can reach 7.5 × 10−17 and 1.3 × 10−10 respectively. The predicted ratio of Br(μ → 3e)/Br(τ → 3e) is also larger and almost parameter independent. These differences make the two ansatz easily distinguishable for future experiments.
119300824
Higher harmonic anisotropic flow measurements of charged particles at 2.76 TeV with the ALICE detector
We report the measurements of elliptic flow $v_{2}$, as well as higher harmonics triangular flow $v_{3}$ and quadrangular flow $v_{4}$, in $\sqrt{s_{_{NN}}} =$ 2.76 TeV Pb--Pb collisions, measured with the ALICE detector. We show that the measured elliptic and triangular flow can be understood from the initial spatial anisotropy and its event--by--event fluctuations. The resulting fluctuations of $v_{2}$ and $v_{3}$ are also discussed.