Dimensionally reduced SYM$_4$ at large-$N$: an intriguing Coulomb approximation

TL;DR

This paper investigates a Coulomb approximation of dimensionally reduced super Yang Mills theory in two dimensions, revealing string-like interactions and partial supersymmetry preservation through numerical analysis of eigenvalues and eigenvectors.

Contribution

It introduces a Coulomb approximation preserving an ${ m N}=(1,1)$ subgroup, extending 't Hooft's model to multiple partons and providing numerical evidence of string-like behavior.

Findings

Eigenvalues and eigenvectors computed for 2-4 partons

Confirmation of string-like interactions with expected tension

Partial preservation of supersymmetry in the spectrum

Abstract

We consider the light-cone (LC) gauge and LC quantization of the dimensional reduction of super Yang Mills theory from four to two dimensions. After integrating out all unphysical degrees of freedom, the non-local LC Hamiltonian exhibits an explicit ${\cal N}=(2,2)$ supersymmetry. A further SUSY-preserving compactification of LC-space on a torus of radius $R$, allows for a large-$N$ numerical study where the smooth large-$R$ limit of physical quantities can be checked. As a first step, we consider a simple, yet quite rich, "Coulomb approximation" that maintains an ${\cal N}=(1,1)$ subgroup of the original supersymmetry and leads to a non-trivial generalization of 't Hooft's model with an arbitrary --but conserved-- number of partons. We compute numerically the eigenvalues and eigenvectors both in momentum and in position space. Our results, so far limited to the sectors with 2, 3 and 4 partons, directly and quantitatively confirm a simple physical picture in terms of a string-like interaction with the expected tension among pairs of nearest-neighbours along the single-trace characterizing the large-$N$ limit. Although broken by our approximation, traces of the full ${\cal N}=(2,2)$ supersymmetry are still visible in the low-lying spectrum.