IAS Amplitudes Group Meeting

Abstract: A recursive extension of $\phi^3$ amplitudes was discovered in 2019 by CEGM.  The first layer is a familiar integral over the positive moduli space $M^+_{0,n}$; the second layer is an integral over the moduli space of polygons in the projective plane; more precisely, and more generally, one evaluates the Laplace transform of the positive tropical Grassmannian $Trop^+G(k,n)$.  We review that construction, and then classify all linear zero-preserving deformations of the resulting amplitude, generalizing a recently discovered formula for nonlinear sigma model pion amplitudes.