Renormalization and Supersymmetry Breaking Phenomenology

Abstract

In this thesis we address some issues of current interest in particle physics and quantum field theory. First we give an introduction to renormalized perturbation theory and loop computations in QFT. QCD is used as an example and it is explicitly renormalized to first order, with all counterterms computed. The beta-function is derived and used to show that, at present energies, QCD is asymptotically free. Secondly we give a short introduction to supersymmetry: its algebra, superfields and SUSY breaking. We present a simple model (the O’Raifeartaigh model) and show how to deal with the case of strong SUSY breaking in a manifestly supersymmetry invariant way. Finally we compute the tree level cross section for production of SUSY breaking hidden particles at the LHC, mediated to the MSSM via a very specific model (semi-direct gauge mediation). Unfortunately, the result is that the cross section is too small to give any sign at the LHC