Executive Summary : | Universal Extra-Dimension (UED) scenarios are exciting proposals beyond the Standard Model (SM) to address shortcomings such as the lack of a candidate for dark matter (DM), an explanation for the number of fermions generation, and proton stability. However, these UED models have a significant shortcoming: the absence of neutrino masses. The minimal UED (mUED) model, which is characterized by a single flat universal extra dimension, has been ruled out from WMAP/PLANCK relic density data and direct searches for the Kaluza-Klien (KK) particles at the Large Hadron Collider (LHC) experiment.
Several extensions of mUED have been proposed to evade collider and dark matter constraints, but they preserve lepton-number and fail to generate Majorana masses for neutrinos. This project aims to search for next-to-minimal realizations of mUED scenarios that do not preserve lepton-number conservation and result in tiny Majorana masses for neutrinos. To achieve a lepton number violation (LNV), one needs to enlarge the gauge structure and/or field content of the SM.
The project plans to construct UED models with enlarged field/gauge structure the SM and study the phenomenological consequences in neutrino mass, DM, and collider experiments. Similar ideas have been extensively studied in supersymmetric models, but they are missing in the context of extra-dimensional scenarios. |