Limits of the Standard Model

Abstract

Supersymmetry is one of the most plausible extensions of the Standard Model, since it is well motivated by the hierarchy problem, supported by measurements of the gauge coupling strengths, consistent with the suggestion from precision electroweak data that the Higgs boson may be relatively light, and provides a ready-made candidate for astrophysical cold dark matter. In the first lecture, constraints on supersymmetric models are reviewed, the problems of fine-tuning the electroweak scale and the dark matter density are discussed, and a number of benchmark scenarios are proposed. Then the prospects for discovering and measuring supersymmetry at the LHC, linear colliders and in non-accelerator experiments are presented. In the second lecture, the evidence for neutrino oscillations is recalled, and the parameter space of the seesaw model is explained. It is shown how these parameters may be explored in a supersymmetric model via the flavour-changing decays and electric dipole moments of charged leptons. It is shown that leptogenesis does not relate the baryon asymmetry of the Universe directly to CP violation in neutrino oscillations. Finally, possible CERN projects beyond the LHC are mentioned.