From Gross-Manes to Alday-Maldacena

Abstract

Minimal surfaces govern the classical limit of several important observables in string theory. Two basic examples are the Gross--Manes saddle for high-energy string scattering in flat space and the Alday--Maldacena surface for gluon scattering at strong coupling in ${\cal N}=4$ SYM. In this paper we study a family of null polygonal minimal surfaces in AdS interpolating between these two regimes by moving the cusps from a small region deep in the bulk to the AdS boundary. We do this both numerically and -- in interesting simplifying limits -- analytically. In particular, we derive the leading AdS-radius correction around flat space and show that the resulting classical amplitude agrees with the recent prediction of Alday, Armanini, Häring, and Zhiboedov, supporting an underlying worldsheet description of their bootstrap construction.