Oscar Zapata

Radiative seesaw model : Warm dark matter, collider signatures, and lepton flavor violating signals

INTRODUCTION: Solar [1], atmospheric [2], and reactor [3] neutrino experiments have demonstrated that neutrinos have mass and nonzero mixing angles among the different generations. On the other hand, observations of the cosmic microwave background, primordial abundances of light elements, and large scale structure formation have firmly established that most of the mass of the Universe consists of dark matter (DM) [4]. These experimental results are at present the most important evidences for physics beyond the standard model. There are several ways in which neutrino masses can be generated. Certainly the best-known mechanism to generate small Majorana neutrino masses is the seesaw [5]. However, a large variety of models exists in which lepton number is broken near or at the electroweak scale. Examples are supersymmetric models with explicit or spontaneous breaking of R parity [6,7], models with Higgs triplets [8], pure radiative models at one-loop [9] or at two-loop [10] order, and models in which neutrino masses are induced by leptoquark interactions [11].

Models with radiative neutrino masses and viable dark matter candidates

A bstractWe provide a list of particle physics models at the TeV-scale that are compatible with neutrino masses and dark matter. In these models, the Standard Model particle content is extended with a small number (≤ 4) of scalar and fermion fields transforming as singlets, doublets or triplets under SU(2), and neutrino masses are generated radiatively via 1-loop diagrams. The dark matter candidates are stabilized by a Z2 symmetry and are in general mixtures of the neutral components of such new multiplets. We describe the particle content of each of these models and determine the conditions under which they are consistent with current data. We find a total of 35 viable models, most of which have not been previously studied in the literature. There is a great potential to test these models at the LHC not only due to the TeV-scale masses of the new fields but also because about half of the viable models contain particles with exotic electric charges, which give rise to background-free signals. Our results should serve as a first step for detailed analysis of models that can simultaneously account for dark matter and neutrino masses.

FIMP realization of the scotogenic model

The scotogenic model is one of the simplest scenarios for physics beyond the Standard Model that can account for neutrino masses and dark matter at the TeV scale. It contains another scalar doublet and three additional singlet fermions (Ni), all odd under a Z2 symmetry. In this paper, we examine the possibility that the dark matter candidate, N1, does not reach thermal equilibrium in the early Universe so that it behaves as a Feebly Interacting Massive Particle (FIMP). In that case, it is found that the freeze-in production of dark matter is entirely dominated by the decays of the odd scalars. We compute the resulting dark matter abundance and study its dependence with the parameters of the model. The freeze-in mechanism is shown to be able to account for the observed relic density over a wide range of dark matter masses, from the keV to the TeV scale. In addition to freeze-in, the N1 relic density receives a further contribution from the late decay of the next-to-lightest odd particle, which we also analyze. Finally, we consider the possibility that the dark matter particle is a WIMP but receives an extra contribution to its relic density from the decay of the FIMP (N1). In this case, important signals at direct and indirect detection experiments are generally expected.

Gravitino dark matter and neutrino masses with bilinear R-parity violation

Bilinear

Indirect detection of gravitino dark matter including its three-body decays

R

Direct Detection of Fermion Dark Matter in the Radiative Seesaw Model

-parity violation provides an attractive origin for neutrino masses and mixings. In such schemes the gravitino is a viable decaying dark matter particle whose

Decaying Neutralino Dark Matter in Anomalous U(1)(H) Models

R

Fermion dark matter from SO(10) GUTs

-parity violating decays lead to monochromatic photons with rates accessible to astrophysical observations. We determine the parameter region allowed by gamma-ray line searches, dark matter relic abundance, and neutrino oscillation data, obtaining a limit on the gravitino mass

The Fermi-LAT gamma-ray excess at the Galactic Center in the singlet-doublet fermion dark matter model

{m}_{\stackrel{\texttildelow{}}{G}}\ensuremath{\lesssim}1\char21{}10\text{ }\text{ }\mathrm{GeV}

Baryonic violation of

corresponding to a relatively low reheat temperature