<b>Department Colloquia</b><br>Exciting New Approaches to Particle Scattering Amplitudes<br><b>Speaker: Henriette Elvang (U-M)</b>
Wednesday, January 25, 2012
340 West Hall
Speaker: Henriette Elvang (U-M)Particle scattering processes at experiments such as the Large Hadron Collider at CERN can be described by scattering amplitudes. In standard quantum field theory courses, students learn to calculate amplitudes using Feynman diagram methods. This is a wonderful method for a process like e- + e+ ® µ- + µ+, but it is highly challenging for a process like gluon + gluon ® 5 gluons, which requires 149 diagrams even at the leading order in perturbation theory. It turns out, however, that the result for such gluon scattering processes is remarkably simple: in some cases the sum of diagrams reduces to just a single term! In recent years, new methods for calculating scattering amplitudes have been developed, and they have revealed that amplitudes have a surprisingly rich mathematical structure. The applications of these new methods range from calculations of processes relevant for LHC physics to theoretical explorations of quantum gravity. I will give an introduction to these new approaches to scattering processes and their applications.