## Lie Groups Seminar

Thomas LamUniversity of Michigan
From string theory amplitudes to positive geometries
Friday, November 8, 2019 - 3:30pm
Malott 406

Genus zero superstring amplitudes are integrals over the
moduli space $M_{0,n}$ of $n$-points on $P^1$, with the case $n=4$
recovering Euler's beta function. The poles of these meromorphic
functions exhibit a rich combinatorial structure, matching that of a
polytope known as the associahedron. We will explain how this can be
understood using the new notion of "positive geometries", and how this
leads to the definition of stringy integrals for any polytope.

This talk will be based on various joint works with Nima Arkani-Hamed,
Yuntao Bai, Song He, Marcus Spradlin and Hugh Thomas.