The Phenomenology of Beyond the Standard Model Scalars due to Extended Symmetries with New Fermions[HBNI Th117]

Abstract

This thesis is structured as follows. In Chapter 2 of the thesis, the Low-Skiba-Smith (LSS) model i.e. the SU (6)/Sp(6) little-Higgs model is studied in detail along with a brief discussion on various little-Higgs models, which include the littlest Higgs model, minimal-moose model etc. The gauge and Yukawa sector of the LSS model are described, pointing out the presence of a 2HDM structure with VLFs there. In Chapter 3, the properties of the 2HDM scalar potential of the LSS model are studied. The parameter space of the LSS model after imposing the 8 TeV LHC constraints is also presented in this chapter. The production and decay modes of the neutral and charged BSM scalars of the LSS model are studied in detail. It is shown in Chapter 4, how the gauged B −L model where the SM is extended by one U (1) B − L symmetry, can generate the observed tiny neutrino mass and present a dark matter candidate. The new particles that are introduced in the model for neutrino mass generation, are also listed. In Chapter 5, one heavy scalar of the gauged B − L model with mass of 750 GeV is chosen to be studied, following the earlier hint of a diphoton excess at the LHC. The phenomenology of that scalar is discussed, explaining the enhanced cross section of the scalar at the diphoton channel. Non-observation of any excess in the other channels and the decay width of the scalar are also discussed. In Chapter 6, all the main results of the thesis are summarized, providing a phenomenological overview of the models.