A complete survey of texture zeros in the lepton mass matrices

We perform a systematic and complete analysis of texture zeros in the lepton mass matrices and identify all viable and maximally restrictive cases of pairs (M_\ell, M_D) and (M_\ell, M_L), where M_\ell, M_D and M_L are the charged-lepton, Dirac neutrino and Majorana neutrino mass matrices, respectively. To this end, we perform a thorough analysis of textures which are equivalent through weak-basis permutations. Furthermore, we introduce numerical measures for the predictivity of textures and apply them to the viable and maximally restrictive texture zero models. It turns out that for Dirac neutrinos these models can at most predict the smallest neutrino mass and the CKM-type phase of the mixing matrix. For Majorana neutrinos most models can, in addition, predict the effective neutrino mass for neutrinoless double beta decay. Apart from one model, which has marginal predictive power with respect to sin^2(theta_23), no other model can predict any of the already measured observables.Comment: 32 pages, 1 figure; corrections in the computer code, numerical analysis repeated, conclusions almost unchanged, changes in tables 9-1

Residual Z2 x Z2 symmetries and lepton mixing

We consider two novel scenarios of residual symmetries of the lepton mass matrices. Firstly we assume a Z2 x Z2 symmetry G_ell for the charged-lepton mass matrix and a Z2 symmetry G_nu for the light neutrino mass matrix. With this setting, the moduli of the elements of one column of the lepton mixing matrix are fixed up to a reordering. One may interchange the roles of G_ell and G_nu in this scenario, thereby constraining a row, instead of a column, of the mixing matrix. Secondly we assume a residual symmetry group G_ell \cong Zm (m>2) which is generated by a matrix with a doubly-degenerate eigenvalue. Then, with G_nu \cong Z2 x Z2 the moduli of the elements of a row of the lepton mixing matrix get fixed. Using the library of small groups we have performed a search for groups which may embed G_ell and G_nu in each of these two scenarios. We have found only two phenomenologically viable possibilities, one of them constraining a column and the other one a row of the mixing matrix.Comment: 14 pages, 1 figur

Systematic analysis of finite family symmetry groups and their application to the lepton sector

In this work we will investigate Lagrangians of the standard model extended by three right-handed neutrinos, and the consequences of invariance under finite groups G for lepton masses and mixing matrices are studied. The main part of this work is the systematic analysis of finite subgroups of SU(3). The analysis of these groups may act as a toolkit for future model building.Comment: Diploma thesis, University of Vienna, June 2009, 227 pages, 1 figure; minor errors correcte

A complete survey of texture zeros in general and symmetric quark mass matrices

We perform a systematic analysis of all possible texture zeros in general and symmetric quark mass matrices. Using the values of masses and mixing parameters at the electroweak scale, we identify for both cases the maximally restrictive viable textures. Furthermore, we investigate the predictive power of these textures by applying a numerical predictivity measure recently defined by us. With this measure we find no predictive textures among the viable general quark mass matrices, while in the case of symmetric quark mass matrices most of the 15 maximally restrictive textures are predictive with respect to one or more light quark masses.Comment: 11 pages, no figure

Supersymmetric Majoron Inflation

We propose supersymmetric Majoron inflation in which the Majoron field $\Phi$ responsible for generating right-handed neutrino masses may also be suitable for giving low scale "hilltop" inflation, with a discrete lepton number $Z_N$ spontaneously broken at the end of inflation, while avoiding the domain wall problem. In the framework of non-minimal supergravity, we show that a successful spectral index can result with small running together with small tensor modes. We show that a range of heaviest right-handed neutrino masses can be generated, $m_N\sim 10^1-10^{16}$ GeV, consistent with the constraints from reheating and domain walls.Comment: 27 pages, 3 figure

Comments on the classification of the finite subgroups of SU(3)

Many finite subgroups of SU(3) are commonly used in particle physics. The classification of the finite subgroups of SU(3) began with the work of H.F. Blichfeldt at the beginning of the 20th century. In Blichfeldt's work the two series (C) and (D) of finite subgroups of SU(3) are defined. While the group series Delta(3n^2) and Delta(6n^2) (which are subseries of (C) and (D), respectively) have been intensively studied, there is not much knowledge about the group series (C) and (D). In this work we will show that (C) and (D) have the structures (C) \cong (Z_m x Z_m') \rtimes Z_3 and (D) \cong (Z_n x Z_n') \rtimes S_3, respectively. Furthermore we will show that, while the (C)-groups can be interpreted as irreducible representations of Delta(3n^2), the (D)-groups can in general not be interpreted as irreducible representations of Delta(6n^2).Comment: 15 pages, no figures, typos corrected, clarifications and references added, proofs revise