Effective theory for fermionic extensions of the Standard Model

Many BSM theories include extensions of the fermionic content of the Standard Model. Typically the new particles are very heavy, so that a smart way to deal with them is by means of the effective theory approach. In this thesis we are interested in new fermions admitting Yukawa-like couplings ΨHq between the Higgs doublet and any Standard Model fermion. After a general overview of the possible extensions compatible with SU(3)×SU(2)×U(1) gauge invariance, we'll focus on a particular vector-like quark of charges (3_c,2_W, 7/6_Y). For this model we will first perform a review of the known results present in literature and then move towards the derivation of the effective theory, which will be computed up to 1-loop by means of the functional integral method. Finally by confronting the obtained Wilson coefficients with their experimental constraints we will obtain new bounds on the coupling constants of this model.