Grant: Subatomic Physics Envelope - Individual

The Standard Model of Particle Physics is one of the most successful scientific theories in history. It can explain a wide range of subatomic phenomena in terms of a few symmetry principles and a handful of constants of nature. There are however, very good reasons to believe that the Standard Model is not the final answer to questions about the fundamental structure of matter. On one hand, there are theoretical concerns about the tuning of the parameters in the model. On the other hand, experimental evidence such as the neutrino flavour oscillations and the existence of dark matter (crucial for the formation of galaxies) remains unexplained in the Standard Model. It is widely believed that the solution to these puzzles requires the existence of new particles and/or new interactions. Unfortunately, although many predictions of beyond the Standard Model physics are available, no conclusive proof of new particles or interactions exists. There are two possible explanations as to why new particles may have escaped detection so far. First, they could be too heavy to be produced in current experiments. Most of my research has been concentrated so far on this idea, and in part of my new research project, I would like to revisit this possibility, and perform a careful study of the assumptions involved (using newly developed software), with the purpose of widening the parameter space still available for new particles and new interactions. A second possibility is that the new particles are hidden, because they couple so feebly to ordinary matter. It may be that the rate at which they are produced is too small, or alternatively, that they form a compressed spectrum, that is, one which does not easily yield observed signals. In this case, the most promising strategy would be to make more precise measurements, and to increase the number of events in experiments (intensity frontier) to find them. I propose to devise some searches at the LHC by choosing observables with little interference from the background, and complimentary to searching in proton-proton collisions, to look for these particles in heavy ion collisions.