K. T. Mahanthappa

CKM and tri-bimaximal MNS matrices in a SU(5)×T(d) model

Abstract We propose a model based on SU ( 5 ) × T ( d ) which successfully gives rise to near tri-bimaximal leptonic mixing as well as realistic CKM matrix elements for the quarks. The Georgi–Jarlskog relations for three generations are also obtained. Due to the T ( d ) transformation property of the matter fields, the b-quark mass can be generated only when the T ( d ) symmetry is broken, giving a dynamical origin for the hierarchy between m b and m t . There are only nine operators allowed in the Yukawa sector up to at least mass dimension seven due to an additional Z 12 × Z 12 ′ symmetry, which also forbids, up to some high orders, operators that lead to proton decay. The resulting model has a total of nine parameters in the charged fermion and neutrino sectors, and hence is very predictive. In addition to the prediction for θ 13 ≃ θ c / 3 2 , the model gives rise to a sum rule, tan 2 θ ⊙ ≃ tan 2 θ ⊙ , TBM − 1 2 θ c cos β , which is a consequence of the Georgi–Jarlskog relations in the quark sector. This deviation could account for the difference between the experimental best fit value for the solar mixing angle and the value predicted by the tri-bimaximal mixing matrix.

Group Theoretical Origin of CP Violation

Abstract We propose the complex group theoretical Clebsch–Gordon coefficients as a novel origin of CP violation. This is manifest in our model based on SU ( 5 ) combined with the T ′ group as the family symmetry. The complex CG coefficients in T ′ lead to explicit CP violation which is thus geometrical in origin. The predicted CP violation measures in the quark sector are consistent with the current experimental data. The corrections due to leptonic Dirac CP violating phase gives the experimental best fit value for the solar mixing angle, and we also gets the right amount of the baryonic asymmetry.

From the CKM matrix to the Maki-Nakagawa-Sakata matrix: A model based on supersymmetric SO(10)xU(2){sub F} symmetry

We construct a realistic model based on SUSY SO(10) with U(2) flavor symmetry. In contrast with the commonly used effective operator approach, 126-dimensional Higgs fields are used to construct the Yukawa sector. R-parity symmetry is thus preserved at low energies. The Dirac and right-handed Majorana mass matrices in our model have very small mixings and they combine with the seesaw mechanism resulting in large leptonic mixing. The symmetric mass textures arising from the left-right symmetry breaking chain of SO(10) give rise to very good predictions; 15 masses (including three right-handed Majorana neutrino masses) and six mixing angles are predicted by 11 parameters. Both the vacuum oscillation and LOW solutions are favored for the solar neutrino problem.

CP Violation in a Supersymmetric SO(10) x U(2)_{F} Model

A model based on SUSY

Inflation at low scales: General analysis and a detailed model

\mathrm{SO}(10)

Tri-bimaximal (TBM) neutrino mixing and quark CKM Matrix in a SU(5) x (d)T model

combined with

Combined study of b{yields}s{gamma} and the muon anomalous magnetic moment in gauge-mediated supersymmetry breaking models

U(2)

Neutrino Mass Models: circa 2008

family symmetry constructed recently by the authors is generalized to include phases in the mass matrices leading to

Consequences of scalar loops on gauge symmetry hierarchies

\mathrm{CP}

Low scale seesaw, electron EDM and leptogenesis in a model with spontaneous CP violation

violation. In contrast with the commonly used effective operator approach,