Some properties of the Alday-Maldacena minimum

Abstract

The Alday-Maldacena solution, relevant to the n=4 gluon amplitude in N=4 SYM at strong coupling, was recently identified as a minimum of the regularized action in the moduli space of solutions of the AdS_5 sigma-model equations of motion. Analogous solutions of the Nambu-Goto equations for the n=4 case are presented and shown to form (modulo the reparametrization group) an equally large but different moduli space, with the Alday-Maldacena solution at the intersection of the sigma-model and Nambu-Goto moduli spaces. We comment upon the possible form of the regularized action for n=5. A function of moduli parameters z_a is written, whose minimum reproduces the BDDK one-loop five-gluon amplitude. This function may thus be considered as some kind of Legendre transform of the BDDK formula and has its own value independently of the Alday-Maldacena approach.