New Physics at the TeV Scale
  The Standard Model of particle physics is assumed to be a low-energy effective theory with new physics theoretically motivated to be around TeV scale. The dissertation presents theories with new physics beyond the Standard Model at the TeV scale testable in the current High Energy Colliders. The study on leptoquarks gauge bosons in reference to TopSU(5) model in chapter 2 showed that their discovery mass range extends upto 1.5 TeV at 14 TeV LHC with luminosity of 100 $fb^{-1}$. On the other hand, in chapter 3 we studied the collider phenomenology of TeV scale mirror fermions in Left-Right Mirror model finding that the reaches for the mirror quarks goes upto $750$ GeV at the $14$ TeV LHC with $~300 ~fb^{-1}$ luminosity. In chapter 4 we have enlarged the bosonic symmetry to fermi-bose symmetry e.g. supersymmetry and have shown that SUSY with non-universalities in gaugino or scalar masses within high scale SUGRA set up can still be accessible at LHC with 14 TeV. In chapter 5, we performed a study in respect to the $e^+e^-$ collider and find that precise measurements of the higgs boson mass splittings upto $\sim 100$ MeV may be possible with high luminosity in the International Linear Collider (ILC). In chapter 6 we have shown that the experimental data on neutrino masses and mixings are consistent with the proposed 4/5 parameter Dirac neutrino models yielding a solution for the neutrino masses with inverted mass hierarchy and large CP violating phase $\delta$ and thus can be tested experimentally. Chapter 7 incorporates a warm dark matter candidate in context of two Higgs doublet model. The model has several testable consequences at LHC. This dissertation presents an endeavor to study beyond standard model (BSM) physics at the TeV scale with testable signals in the Colliders. 
Shreyashi Chakdar
hep-ph