UC Berkeley

The Standard Model of particle physics has thus far proven extremely effective at describing the composition and interactions of matter we observe. However, theoretical considerations, such as the large hierarchy between the weak and Planck scales, and experimental evidence, such as the observation of non-baryonic dark matter, suggest the possibility of new physics beyond the Standard Model (BSM). In many scenarios, such new physics would occur around the TeV scale, and therefore has an excellent chance of being seen at current and future collider experiments.

Following a review of the standard model, its problems, and some new physics scenarios, we explore a number of ways in which colliders may be used to study such new physics. We first discuss a technique for determining the masses of new particles in single-step decay chains, a task which is typically complicated by missing energy associated with discrete symmetries prevalent in BSM models. We then address the determination of the spins of new particles at colliders, developing a model-independent technique and demonstrating how it could be used to distinguish two specific models, supersymmetry and universal extra dimensions, at a future linear collider. We further demonstrate that the effectiveness of this technique could be realized experimentally using existing data from both e+e- and hadron colliders. Finally, we turn away from model-independent techniques and propose a search for color sextet scalars, which could be copiously produced at the Large Hadron Collider. Pair production of such particles could potentially be seen in the relatively clean same-sign dilepton + jets + missing energy channel, for which we propose an effective reconstruction of the sextet pair.