Topic: Scattering amplitudes

Scattering amplitudes constrain effective field theories from the bottom up through general consistency requirements, including unitarity and causality. Existing bounds mainly use four-point amplitudes. This talk explains how amplitudes with more external points supply additional constraints beyond the four-point analysis, and demonstrates the method through an application to Large-Nc quantum chromodynamics.

Tree-level open string amplitudes are integrals over the moduli space of n points on the projective line, and their field theory limit is the Cachazo-He-Yuan formula for tr(\Phi^3) amplitudes. Joint work with Freddy Cachazo, Alfredo Guevara and Sebastián Mizera (CEGM) replaces the line by P^(k-1), giving amplitude-like objects whose Feynman diagrams are higher-dimensional polyhedral complexes rather than trees. After reviewing this framework, I will discuss recent progress on new factorization patterns which appear and linear zero-preserving deformations, which produce nonlinear sigma model am