Abstract
In this talk, we will discuss Universal Extra Dimensional models (UED) in its basic and non-minimal version (nmUED). Non-minimality in Universal Extra Dimensional (UED) framework is realized by adding boundary localized terms (BLT). We will discuss the unitarity constraints in gauge and scalar sectors. We shall show that some of the tree-level two-body scattering amplitudes in gauge and scalar sectors do not respect partial wave unitarity. Unitarity of scalar sector of this model leads to an upper bound on gauge or scalar BLT parameter which depends on the maximum number of Kaluza-Klein (KK) mode considered in the analysis. We shall also show the limit on compactification radius of UED in view of the Zbb coupling. For suitable choice of BLT parameters (which is permissible from unitarity analysis), 95% C.L. lower limit on inverse of compactification radius comes out to be in the range of 1 TeV in the framework of nmUED. Finally, we will discuss some flavor changing top quark decays. In UED these decay rates do not change much from their Standard Model (SM) values. However, in nmUED these decay rates can be higher than SM for specific choices of the BLT parameters for a certain range of inverse compactification radius. But these model parameters may lead to Kaluza-Klein particle masses that are in tension with the LHC and LEP bounds.
