Talks

To a first approximation, everything that happens at the Large Hadron Collider at CERN is a strong interaction process. If signals of supersymmetric particles or other new states are found at the LHC, the events that produce those signals will represent parts per trillion of the total sample of proton-proton scattering events and parts per billion of the sample of events with hard scattering of quarks and gluons. Can we predict the rates of QCD processes well enough to control their contribution to a tantalizing signal? What physics insights can assist this process? Can string theory help? In this lecture, I will describe the current status of Quantum Chromodynamics and its application to the predictions for hadron colliders. Note: Those who would like more background on the LHC should attend my talk at the Physics Department Colloquium of the University of Waterloo, Thursday, Jan. 13, at 4:00 pm: The Search for New Elementary Particles at the CERN Large Hadron Collider

Mathematics and physics can come together to the benefit of both fields, particularly in the case of Calabi-Yau spaces and string theory---our leading attempt to explain the universe to date. The audience will gain a sense of how mathematicians think and approach the world and realize that mathematics does not have to be a wholly abstract discipline, disconnected from everyday phenomena, but it is instead crucial to our understanding of the physical world.

Strong lensing galaxy clusters provide promising probes of cosmological structure formation. Strong lensing halos can be identified in cosmological simulations through ray tracing techniques and their properties measured. Previous studies have found some evidence that strong lensing clusters are more concentrated than expected, with possible explanations including baryonic effects or more exotic physics such as early dark energy. Using Sunyaev-Zeldovich (SZ) observations to measure the mass on large scales and strong lensing mass modeling for small scales, we find that the clusters are more concentrated than expected at the 97% confidence level. We also investigate the placement of lensed images with respect to the SZ gas and Brightest Cluster Galaxy orientations. I will also discuss the redshift evolution of radio Active Galactic Nuclei in clusters, which is relevant for determining cosmological parameters from SZ surveys as well as for understanding the energy budgets in cluster cores.