  We take the Lagrangian of Inert Doublet Model and with unitary gauge
calculate all the possible interactions, after calculating the interactions we
draw the corresponding Feynman diagrams.There after calculate the Scattering
cross section of the processes that contribute in the decay or scattering of DM
candidate. In the concluding chapter we calculate the one loop correction to
the process $HH\to hh$ and see all the possible loop contribution at this
scale.
