  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.
