Renormalization and Supersymmetry Breaking Phenomenology

Abstract

In this thesis we address some issues of current interest in particle physics and quantum field theory (QFT). First we give an introduction to renormalized perturbation theory and loop computations in QFT. Quantum chromodynamics (QCD) is used as an example and it is explicitly renormalized to first order, with all counterterms computed. The β-function is derived and used to show that QCD is asymptotically free. Secondly we give a short introduction to supersymmetry (SUSY): the 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 a hidden vector boson present in a specific model of SUSY breaking (semi-direct gauge mediation). Unfortunately, the resulting cross section is too small to give a signal at the LHC. We also compute the decay rate of the vector boson and show that it is actually a candidate for dark matter.