119220764
The Kobayashi-Maskawa Parametrization of Lepton Flavor Mixing and Its Application to Neutrino Oscillations in Matter
We show that the Kobayashi-Maskawa (KM) parametrization of the 3 X 3 lepton flavor mixing matrix is a useful language to describe the phenomenology of neutrino oscillations. In particular, it provides us with a convenient way to link the genuine flavor mixing parameters (\theta_1, \theta_2, \theta_3 and \delta_KM) to their effective counterparts in matter (\tilde{\theta}_1, \tilde{\theta}_2, \tilde{\theta}_3 and \tilde{\delta}_KM). We rediscover the Toshev-like relation sin \tilde{\delta}_KM sin 2\tilde{\theta}_2 = sin \delta_KM sin 2\theta_2 in the KM parametrization. We make reasonable analytical approximations to the exact relations between the genuine and matter-corrected flavor mixing parameters in two different experimental scenarios: (a) the neutrino beam energy E is above O(1) GeV and (b) E is below O(1) GeV. As an example, the probability of \nu_\mu -> \nu_e oscillations and CP-violating effects are calculated for the upcoming NOvA and Hyper-K experiments.
119257921
Geometry of the effective Majorana neutrino mass in the $0\nu\beta\beta$ decay
The neutrinoless double-beta (0 nu beta beta) decay is a unique process used to identify the Majorana nature of massive neutrinos, and its rate depends on the size of the effective Majorana neutrino mass (ee). We put forward a novel 'coupling-rod' diagram to describe (ee) in the complex plane, by which the effects of the neutrino mass ordering and CP-violating phases on (ee) are intuitively understood. We show that this geometric language allows us to easily obtain the maximum and minimum of vertical bar (ee)vertical bar. It remains usable even if there is a kind of new physics contributing to (ee), and it can also be extended to describe the effective Majorana masses (e mu), (e tau), (mu mu), (mu tau), and (tau tau) which may appear in some other lepton-number violating processes.
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.
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.
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.
119263633
Two Higgs bi-doublet left-right model with spontaneous P and CP violation
A left-right symmetric model with two Higgs bi-doublet is shown to be a consistent model for both spontaneous P and CP violation. The flavor changing neutral currents can be suppressed by the mechanism of approximate global U(1) family symmetry. The constraints from neural K meson mass difference ΔmK are calculated and it is demonstrated that a right-handed gauge boson W2 contribution in box-diagrams with mass well below 1 TeV is allowed due to a cancelation caused by a light-charged Higgs boson with a mass range of 150–300 GeV. The W2 contribution to εK can be suppressed from an appropriate choice of additional CP phases appearing in the right-handed Cabbibo-Kobayashi-Maskawa matrix. The model is also found to be fully consistent with B0 mass difference ΔmB and the mixing induced CP violation sin2βJ/ Ψ, which is usually difficult for the model with only one Higgs bi-doublet. The new physics beyond the standard model can be directly searched at the colliders LHC and ILC.
119440725
Implications from recent measurements on sin 2 beta and muon g-2
The recent data on CP asymmetry in $B->J/\Psi K_S$ and muon g-2 are discussed in the framework of standard model and beyond. Possible new phase effects besides the CKM phase are discussed in the processes concerning CP violation in B decays and muon anomalous magnetic moment (muon g-2). It is found that the new phases will result in difference between angles $beta$ measured from $B->J/\Psi K_S$ and the one from global fit. The ration between them serves as a probe of not only new physics but also new phase besides the CKM phase In the case of muon g-2, the new phase may change the interferences between various contributions. By including the new phases, some cancelations in the real coupling cases can be avoided and the large value of muon g-2 observed in the recent measurements can be understood.
116833844
Weak and strong phases and direct CP violation implied from the charmless B-meson decays
115775190
More precise determination of V-cb & V-ub and direct CP violation in charmless B decays
More precise extractions on the two important CKM matrix elements \V-cb\ and \V-ub\ are presented up to 1/m(Q)(2) corrections, based on the complete heavy-quark effective field theory (HQEFT) of QCD. The HQEFT as a large component QCD provides us with a complete theoretical framework for correctly and systematically evaluating the subleading and higher-order contributions in 1/m(Q) expansion of heavy quarks. A global analysis on charmless B decays is made, based on the isospin and SU(3) flavor symmetry. An isospin relation is found to be very useful for studying SU(3) symmetry-breaking effects of strong phases and exploring new types of electroweak penguin effects. The direct CP violation in charmless B decays is predicted, and its precise measurement is helpful either for testing SU(3) symmetry breaking effects of strong phases or for probing news physics beyond standard model.
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.