Deformations of N=4 SYM and integrable spin chain models

TL;DR

This paper investigates deformations of N=4 SYM theory that preserve integrability, finding that only orbifold models with twisted boundary conditions are fully integrable, and explores the limitations of achieving certain symmetries.

Contribution

It demonstrates that integrability constraints restrict deformations to orbifold models with twisted boundary conditions and shows the challenges in realizing certain quantum group symmetries.

Findings

Only orbifold deformations yield integrable models.

Integrable subsectors are common but do not imply full integrability.

Deformations cannot produce SO_q(6) symmetry from N=4 SYM scalar potential.

Abstract

Beginning with the planar limit of N=4 SYM theory, we study planar diagrams for field theory deformations of N=4 which are marginal at the free field theory level. We show that the requirement of integrability of the full one loop dilatation operator in the scalar sector, places very strong constraints on the field theory, so that the only soluble models correspond essentially to orbifolds of N=4 SYM. For these, the associated spin chain model gets twisted boundary conditions that depend on the length of the chain, but which are still integrable. We also show that theories with integrable subsectors appear quite generically, and it is possible to engineer integrable subsectors to have some specific symmetry, however these do not generally lead to full integrability. We also try to construct a theory whose spin chain has quantum group symmetry SO_q(6) as a deformation of the SO(6) R-symmetry structure of N=4 SYM. We show that it is not possible to obtain a spin chain with that symmetry from deformations of the scalar potential of N=4 SYM. We also show that the natural context for these questions can be better phrased in terms of multi-matrix quantum mechanics rather than in four dimensional field theories.