University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Thursday, April 9th 2015
12:15 pm:
Speaker: David McGady (Princeton)
Subject: Constructing massless S-matrices

I will discuss several aspects of modern treatments of the on-shell S-matrix. In particular, I will give an inductive proof of on-shell recursion relations --- due to Britto, Cachazo, Feng, and Witten (BCFW) --- to graviton amplitudes in four dimensions. Unlike previous proofs of applicability in the literature, this proof relies exclusively on on-shell reasoning. As a corollary of this analysis, we show that the formerly mysterious ``bonus'' scaling of graviton amplitudes under large BCFW-shifts follows simply from Bose symmetry. I will also discuss a way to extract many beautiful, classic, no-go theorems from straightforward analysis of four-point scattering amplitudes.

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