We present a new model of radiative neutrino mass generation wherein TeV scale leptoguark scalars induce tiny neutrino masses as two-loop radiative corrections. The neutrino oscillation parameter sin 2 θ 13 is predicted to be close to the current experimental limit within the model. Rare lepton flavor violating processes mediated by leptoquarks have an interesting pattern: µ → eγ may be suppressed, while µ → 3e and µ − e conversion in nuclei are within reach of the next generation experiments. New CP violating contributions to B s −B s mixing via leptoquark box diagrams are in a range that can explain the recently reported discrepancy with the standard model. D − s → ℓ − ν decays mediated by leptoquarks brings theory and experiment closer, removing an observed 2σ anomaly. Muon g − 2 receives new positive contributions, which can resolve the discrepancy between theory and experiment. The leptoquarks of the model are accessible to the LHC, and their decay branching ratios probe neutrino oscillation parameters. *

Abstract:We perform an analysis of Higgs portal models of dark matter (DM), where DM is light enough to contribute to invisible Higgs decays. Using effective field theory we show that DM can be a thermal relic only if there are additional light particles present with masses below a few 100 GeV. We give three concrete examples of viable Higgs portal models of light DM: (i) the SM extended by DM scalar along with an electroweak triplet and a singlet, (ii) a Two Higgs Doublet Model of type II with additional scalar DM, (iii) SM with DM and an extra scalar singlet that is lighter than DM. In all three examples the B(h → invisible) constraint is not too restrictive, because it is governed by different parameters than the relic abundance. Additional light particles can have implications for flavor violation and collider searches.

In this work we study the viable parameter space of the scalar sector in the type-II seesaw model. In identifying the allowed parameter space, we employ constraints from low energy precision measurements, theoretical considerations and the 125-GeV Higgs data. These tools prove effective in constraining the model parameter space. Moreover, the triplet also offers a rich collider phenomenology from having additional scalars that have unique collider signatures. We find that direct collider searches for these scalars can further probe various parts of the viable parameter space. These parts can be parametrized by the electroweak scalar triplet vacuum expectation value, the mass splitting of the singly-and doubly-charged scalars, and the doubly-charged Higgs mass. We find that different regions of the viable parameter space give rise to different collider signatures, such as the same-sign dilepton, the same-sign W and the multilepton signatures. By investigating various LEP and LHC measurements, we derive the most updated constraints over the whole range of parameter space of the type-II seesaw model.

We study the renormalization group equations of Ma's scotogenic model, which generates an active neutrino mass at 1-loop level. In addition to other benefits, the main advantage of the mechanism exploited in this model is to lead to a natural loop-suppression of the neutrino mass, and therefore to an explanation for its smallness. However, since the structure of the neutrino mass matrix is altered compared to the ordinary type I seesaw case, the corresponding running is altered as well. We have derived the full set of renormalization group equations for the scotogenic model which, to our knowledge, had not been presented previously in the literature. This set of equations reflects some interesting structural properties of the model, and it is an illustrative example for how the running of neutrino parameters in radiative models is modified compared to models with tree-level mass generation. We also study a simplified numerical example to illustrate some general tendencies of the running. Interestingly, the structure of the RGEs can be exploited such that a bimaximal leptonic mixing pattern at the high-energy scale is translated into a valid mixing pattern at low energies, featuring a large value of θ 13. This suggests very interesting connections to flavour symmetries. *

A new model of radiative neutrino masses generated via two-loop diagrams is proposed involving a charge 2/3 vector-like quark and a doublet of leptoquark scalars.This model predicts one of the neutrinos to be massless and admits both the normal and inverted neutrino mass hierarchies with correlated predictions for ℓ i → ℓ j + γ branching ratios. New contributions to CP violation in B 0 s − B 0 s mixing arise in the model through leptoquark box diagrams, which can explain the anomalous dimuon events reported by the DØ collaboration. These leptoquarks, with masses below 500GeV, also provide a natural resolution to the apparent discrepancy in the measured values of the CP violation parameters sin 2β and