Sterile neutrinos are among the most attractive extensions of the SM to generate the light neutrino masses observed in neutrino oscillation experiments.
When the sterile neutrinos are subject to a protective symmetry, they can have masses around the electroweak scale and potentially large neutrino Yukawa couplings, which makes them testable at planned future particle colliders.
In this talk...
The existence of non-baryonic Dark Matter (DM) is well established by cosmological and astrophysical probes, however its detailed nature still remains elusive. Among the extensions of the Standard Model explaining the DM relic aboundance, the simplest one is the addition of an inert scalar to the theory. In this talk I intend to give a brief review of this scenario and its possible connection...
In many flavour models, the vacuum expectation values of flavon multiplets
form the fermion mass matrices. The VEVs and their symmetries lead to
constraints among the masses and the mixing observables. The presence of
coupling constants (corresponding to various flavon multiplets) leaves
some degrees of freedom of the mass matrices unconstrained. Recently we
introduced a single sextet of...
More than eighty years after they were first proposed, neutrinos still remain an enigma. Although they are an integral part of Standard Model, still we know very little about them. In particular, the Dirac or Majorana nature of neutrinos remains a mystery. For a long time theoretical particle physicists believed that neutrinos must be Majorana in nature and several elegant mass generation...
We systematically analyze the $d=5$ Weinberg operator at 3-loop order. From all possible topologies only a small number of them can generate a genuine 3-loop neutrino mass for which $d=5$ tree-level, 1-loop and 2-loop, as well as $d=7$ up to 1-loop, are guaranteed to be absent. Moreover, from the large list of all possible genuine neutrino mass diagrams, we find that they consist of variations...
We answer the following question: what are the flavour groups and representations providing, in the symmetric limit, an approximate description of lepton masses and mixings? We assume that neutrinos masses are described by the Weinberg operator. We find that in all cases the neutrinos are either anarchical or have an inverted hierarchical spectrum. In the context of SU(5) unification, only the...
We investigate the structure of different softs terms in the context of an A4xSU(5) SUSY GUT model. While starting from a minimal flavour violation (MFV) benchmark point which lies in the correct region for dark matter constraint and giving the experimental value of muon g-2, we perform a scan over the different off-diagonal soft terms and study the impact of the flavour and dark matter...
Flavor symmetries à la Froggatt-Nielsen (FN) provide a compelling way to explain the hierarchies of fermionic masses and mixing angles in the Yukawa sector. In Supersymmetric (SUSY) extensions of the Standard Model where the mediation of SUSY breaking occurs at scales larger than the breaking of flavor, this symmetry must be respected not only by the Yukawas of the superpotential, but by the...
