Physics Beyond the Standard Model: Exotic Leptons and Black Holes at Future Colliders

Abstract

The Standard Model of particle physics has been remarkably successful in describing present experimental results. However, it is assumed to be only a low-energy effective theory which will break down at higher energy scales, theoretically motivated to be around 1 TeV. There are a variety of proposed models of new physics beyond the Standard Model, most notably supersymmetric and extra dimension models. New charged and neutral heavy leptons are a feature of a number of theories of new physics, including the `intermediate scale' class of supersymmetric models. Using a time-of-flight technique to detect the charged leptons at the Large Hadron Collider, the discovery range (in the particular scenario studied in the first part of this thesis) is found to extend up to masses of 950 GeV. Extra dimension models, particularly those with large extra dimensions, allow the possible experimental production of black holes. The remainder of the thesis describes some theoretical results and computational tools necessary to model the production and decay of these miniature black holes at future particle colliders. The grey-body factors which describe the Hawking radiation emitted by higher-dimensional black holes are calculated numerically for the first time and then incorporated in a Monte Carlo black hole event generator; this can be used to model black hole production and decay at next-generation colliders. It is hoped that this generator will allow more detailed examination of black hole signatures and help to devise a method for extracting the number of extra dimensions present in nature.