A Flavor Symmetry Model for Bilarge Leptonic Mixing and the Lepton Masses

We present a model for leptonic mixing and the lepton masses based on flavor symmetries and higher-dimensional mass operators. The model predicts bilarge leptonic mixing (i.e., the mixing angles theta_{12} and theta_{23} are large and the mixing angle theta_{13} is small) and an inverted hierarchical neutrino mass spectrum. Furthermore, it approximately yields the experimental hierarchical mass spectrum of the charged leptons. The obtained values for the leptonic mixing parameters and the neutrino mass squared differences are all in agreement with atmospheric neutrino data, the Mikheyev--Smirnov--Wolfenstein large mixing angle solution of the solar neutrino problem, and consistent with the upper bound on the reactor mixing angle. Thus, we have a large, but not close to maximal, solar mixing angle theta_{12}, a nearly maximal atmospheric mixing angle theta_{23}, and a small reactor mixing angle theta_{13}. In addition, the model predicts theta_{12} ~= pi/4 - theta_{13}.Comment: 41 pages, 4 figures, Elsevier LaTeX. Final version to be published in Nucl. Phys.

CP violating Tri-bimaximal-Cabibbo mixing

In view of the new data from the Daya Bay and RENO collaborations, King has presented a very natural deformation of tri-bimaximal mixing. Here we show that L/E flatness of the e-like event ratio in the atmospheric neutrino data, when coupled with King's observation that the smallest neutrino mixing angle, \theta_{13}, seems to be related to the largest quark mixing angle (the Cabibbo angle \theta_C), leads to a CP violating tri-bimaximal-Cabibbo mixing. King's tri-bimaximal-Cabibbo mixing follows as a leading order approximation from our result.Comment: 6 page

Model for T2K indication with maximal atmospheric angle and tri-maximal solar angle

Recently T2K gives hint in favor of large reactor angle. Most of the models, with tri-bimaximal mixing at the leading order, can not reproduce such a large mixing angle since they predict typically corrections for the reactor angle of the order of the Cabibbo angle. In this letter, we discuss the possibility to have large reactor angle within the T2K region with maximal atmospheric mixing angle and trimaximal solar mixing angle, through the deviation from tri-bimaximal. We derive the structure of neutrino mass matrix that leads to the large reactor angle leaving maximal atmospheric angle and trimaximal solar angle. It is shown that such a structure of neutrino mass matrix can arise in a model with S4 flavor symmetry.Comment: 7 pages, 2 figures, some references added and text improve

Determination of f0−a00f_0 - a_0^0 mixing angle from QCD sum rules

By assuming that the $f_0$ and $a_0^0$ mesons are mixed states of the two-quark - tetraquark, the mixing angle between them is estimated within QCD sum rules method, and it is obtained that the mixing angle is $(6.03 \pm 0.08)^\circ$. Our prediction on mixing angle can be checked in further experiments which can shed light on choosing the "right" structure of $f_0$ and $a_0^0$ mesons

Nonzero θ13\theta_{13} and CP Violation from Broken μ−τ\mu-\tau Symmetry

Nonzero and relatively large of $\theta_{13}$ mixing angle has some phenomenological consequences on neutrino physics beyond the standard model. One of the consequences if the mixing angle $\theta_{13}\neq 0$ is the possibility of the CP violation on the neutrino sector. In order to obtain nonzero $\theta_{13}$ mixing angle, we break the neutrino mass matrix that obey $\mu-\tau$ symmetry by introducing a complex parameter and determine the Jarlskog invariant as a measure of CP violation existence. By using the experimental data as input, we determine the Dirac phase $\delta$ as function of mixing angle $\theta_{13}$Comment: 5 pages, no figure, abstract and section 3 extende

Bi-large neutrino mixing and the Cabibbo angle

Recent measurements of the neutrino mixing angles cast doubt on the validity of the so-far popular tri-bimaximal mixing ansatz. We propose a parametrization for the neutrino mixing matrix where the reactor angle seeds the large solar and atmospheric mixing angles, equal to each other in first approximation. We suggest such bi-large mixing pattern as a model building standard, realized when the leading order value of the reactor angle equals the Cabibbo angle.Comment: 4 pages, 2 figs. v2: matches version appearing in Phys.Rev.D, rapid communication

η−η′\eta-\eta^{\prime} mixing

The $\eta -\eta^{\prime}$ mixing mass term due to the derivative coupling $SU(3)\times SU(3)$ symmetry breaking term, produces an additional momentum-dependent pole term for processes with $\eta^{\prime}$, but is suppressed in the $\eta$ amplitude by a factor $m_{\eta}^{2}/m_{\eta^{\prime}}^{2}$. This seems to be the origin of the two-angle description of the pseudo-scalar decay constants used in the literature. In this paper, by diagonalizing both the mixing mass term and the momentum-dependent mixing term, we show that the $\eta -\eta^{\prime}$ system could be described by a meson field renormalization and a new mixing angle $\theta$ which differs from the usual mixing angle $\theta_{P}$ by a small momentum-dependent mixing $d$ term. This new mixing scheme with exact treatment of the momentum-dependent mixing term, is actually simpler than the perturbation treatment and should be used in any determination of the $\eta -\eta^{\prime}$ mixing angle and the momentum-dependent mixing term. Assuming nonet symmetry for the $\eta_{0}$ singlet amplitude, from the sum rules relating $\theta$ and $d$ to the measured vector meson radiative decays amplitudes, we obtain consistent solutions with $\theta=-(13.99\pm 3.1)^{\circ}$, $d=0.12\pm 0.03$ from $\rho\to\eta\gamma$ and $\eta^{\prime}\to\rho\gamma$ decays, for $\omega$ , $\theta=-(15.47\pm 3.1)^{\circ}$, $d=0.11\pm 0.03$, and for $\phi$, $\theta=-(12.66\pm 2.1)^{\circ}$, $d=0.10\pm 0.03$. It seems that vector meson radiative decays would favor a small $\eta-\eta^{\prime}$ mixing angle and a small momentum-dependent mixing term.Comment: LaTeX, 11 pages, v2, text and references added, to appear in PR

The η−η′\eta - \eta' Mixing Angle Revisited

The value of the $\eta - \eta'$ mixing angle $\theta_P$ is phenomenologically deduced from a rather exhaustive and up-to-date analysis of data including strong decays of tensor and higher-spin mesons, electromagnetic decays of vector and pseudoscalar mesons, $J/\psi$ decays into a vector and a pseudoscalar meson, and other transitions. A value of $\theta_P$ between $-17^\circ$ and $-13^\circ$ is consistent with all the present experimental evidence and the average $\theta_P=-15.5^\circ\pm 1.3^\circ$ seems to be favoured.Comment: 17 pages, LaTeX. 2 references added, some comments on Chiral Perturbation Theor

Determination of the Σ\Sigma--Λ\Lambda mixing angle from QCD sum rules

The $\Sigma$--$\Lambda$ mixing angle is calculated in framework of the QCD sum rules. We find that our prediction for the mixing angle is $(1.00\pm 0.15)^0$ which is in good agreement with the quark model prediction, and approximately two times larger than the recent lattice QCD calculations.Comment: 5 pages, no figures, LaTeX formatte