Related papers: Anarchy and Neutrino Physics
In the framework of seesaw neutrino masses from heavy fermion triplets $(\Sigma^+,\Sigma^0,\Sigma^-)$, the addition of a light fermion singlet $N$ and a heavy scalar triplet $(\rho^+,\rho^0,\rho^-)$ has some important consequences. The new…
Neutrinos are the most elusive particles of the Standard Model. The physics behind their masses remains unknown and requires introducing new particles and interactions. An elegant solution to this problem is provided by the seesaw…
Theories in which neutrino masses are generated by a conventional see-saw mechanism generically yield masses which are O(v^2) in units where M_{Pl}=1, which is naively too small to explain the results from SuperKamiokande. In supersymmetric…
We review theoretical ideas, problems and implications of neutrino masses and mixing angles. We give a general discussion of schemes with three light neutrinos. Several specific examples are analyzed in some detail, particularly those that…
A non-minimal approximation for effective masses of light and heavy neutrinos in the framework of a type-I seesaw mechanism with three generations of sterile Majorana neutrinos which recover the symmetry between quarks and leptons is…
We propose a neutrino mass matrix model in which five neutrino species remain light through the seesaw mechanism within a supersymmetric $3\nu_L+3\nu_R$ framework. We construct such a model based on the nonrenormalizable terms in the…
We discuss all possible schemes with four massive neutrinos inspired by the existing experimental indications in favour of neutrino mixing, namely the atmospheric, solar and LSND neutrino experiments. We argue that the scheme with a…
We discuss two types of neutrino mass matrices which both give $\theta_{23} = 45^\circ$, i.e., a maximal atmospheric mixing angle. We review three models, based on the seesaw mechanism and on simple extensions of the scalar sector of the…
The Majorana nature of neutrinos is strongly motivated from the theoretical and phenomenological point of view. A plethora of neutrino mass models, known collectively as Seesaw models, exist that could generate both a viable neutrino mass…
Status of determination of the neutrino masses and mixing is formulated and possible uncertainties, especially due to presence of the sterile neutrinos, are discussed. The data hint an existence of special ``neutrino'' symmetries. If not…
In a wide class of unified models there is an additional (and possibly dominant) term in the neutrino mass formula that under the simplest assumption takes the form M_{\nu} = (M_N + M_N^T)u/M_G, where M_N is the neutrino Dirac mass matrix,…
The simplest unified extension of the MSSM with bi-linear R--Parity violation naturally predicts a hierarchical neutrino mass spectrum, in which one neutrino acquires mass by mixing with neutralinos, while the other two get mass…
The mixing of three and four massive neutrinos is considered. It is shown that the neutrino oscillation data are not compatible with a hierarchy of couplings in the three-neutrino case. In the case of four neutrinos, a hierarchy of masses…
We consider an extension of the Standard Model with three right-handed (RH) neutrinos and a Dirac pair of extra sterile neutrinos, odd under a discrete $Z_2$ symmetry, in order to have left-right symmetry in the neutrino content and obtain…
We show that the assumption of type II seesaw mechanism for small neutrino masses coupled with $b-\tau$ mass unification in a minimal SUSY SO(10) model leads not only to a natural understanding of large atmospheric mixing angle…
The seesaw mechanism in models with extra dimensions is shown to be generically consistent with a broad range of Majorana masses. The resulting democracy of scales implies that the seesaw mechanism can naturally explain the smallness of…
We propose a Standard Model (SM) extension where neutrinos get masses through a two-loop inverse seesaw mechanism. This naturally explains the smallness of the neutrino masses and allows seesaw mediators to be at the TeV scale with testable…
Non-unitary neutrino mixing in the light neutrino sector is a direct consequence of type-I seesaw neutrino mass models. In these models, light neutrino mixing is described by a sub-matrix of the full lepton mixing matrix and, then, it is…
A neutrino mass model is suggested within an $SU(4)\times U(1)$ -- electroweak theory. The smallness of neutrino masses can be guaranteed by a seesaw mechanism realized through Yukawa couplings to a scalar $SU(4)$-decuplet. In this scheme…
The observed pattern of neutrino mass splittings and mixing angles indicates that their family structure is significantly different from that of the charged fermions. We investigate the implications of these data for the fermion mass…