Planar plane-wave matrix theory at the four loop order: Integrability without BMN scaling

TL;DR

This paper demonstrates four-loop integrability of the SU(N) plane-wave matrix theory in the large N limit, revealing a breakdown of BMN scaling and analyzing the structure of the associated S-matrix and wrapping interactions.

Contribution

It provides the first explicit four-loop computation of the effective Hamiltonian and integrability proof for the planar plane-wave matrix model, including the structure of the S-matrix and scaling properties.

Findings

Established four-loop integrability of the model.

Discovered breakdown of BMN scaling at four loops.

Analyzed wrapping interactions in the context of the model.

Abstract

We study SU(N) plane-wave matrix theory up to fourth perturbative order in its large N planar limit. The effective Hamiltonian in the closed su(2) subsector of the model is explicitly computed through a specially tailored computer program to perform large scale distributed symbolic algebra and generation of planar graphs. The number of graphs here was in the deep billions. The outcome of our computation establishes the four-loop integrability of the planar plane-wave matrix model. To elucidate the integrable structure we apply the recent technology of the perturbative asymptotic Bethe Ansatz to our model. The resulting S-matrix turns out to be structurally similar but nevertheless distinct to the so far considered long-range spin-chain S-matrices of Inozemtsev, Beisert-Dippel-Staudacher and Arutyunov-Frolov-Staudacher in the AdS/CFT context. In particular our result displays a breakdown of BMN scaling at the four-loop order. That is, while there exists an appropriate identification of the matrix theory mass parameter with the coupling constant of the N=4 superconformal Yang-Mills theory which yields an eigth order lattice derivative for well seperated impurities (naively implying BMN scaling) the detailed impurity contact interactions ruin this scaling property at the four-loop order. Moreover we study the issue of ``wrapping'' interactions, which show up for the first time at this loop-order through a Konishi descendant length four operator.