University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Colloquium

Thursday, October 1st 2015
3:35 pm:
Physics and Astronomy Colloquium in 230 STSS/Bruininks Hall
Speaker: Lance Dixon, SLAC/Stanford
Subject: New Approaches to Quantum Scattering and the Payoff for the LHC
Refreshments to be served outside 230 SSTS after the colloquium.

The Large Hadron Collider is renewing its exploration of the energy frontier of particle physics, searching for new particles and interactions beyond the Higgs boson. For the LHC to uncover many types of new physics, the "old physics" produced by the Standard Model must be understood very well. For decades the central theoretical tool for this job was the Feynman diagram. However, Feynman diagrams are just too slow, even on fast computers, to allow adequate precision for complicated events with many jets of hadrons in the final state. Such events constitute formidable backgrounds at the LHC to many searches for new physics. Over the past few years, alternative methods to
Feynman diagrams have come to fruition. The new "on-shell" methods are based on the old principle of unitarity. They can be much more efficient because they exploit the underlying simplicity of scattering amplitudes, and recycle lower-loop information. Farther afield, the
new methods have led to intriguing new results in quantum gravity and in supersymmetric analogs of the Standard Model. I'll explain how and why these methods work, and present recent state-of-the-art results obtained with them.

Faculty Host: Tony Gherghetta

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