Integrable Spin Chain in Superconformal Chern-Simons Theory

TL;DR

This paper investigates the integrability of N=6 superconformal Chern-Simons theory by analyzing the spectrum of single trace operators, constructing related spin chains, and confirming consistency between gauge theory calculations and integrability-based solutions.

Contribution

It constructs an integrable spin chain model for the theory, matches it with perturbative gauge calculations, and explores the spectrum of operators including wrapping effects and Bethe ansatz solutions.

Findings

Spin chain Hamiltonian matches Yang-Baxter solution

Spectrum of operators agrees with supersymmetry predictions

Evidence of nonexistence of mesonic bound states

Abstract

N = 6 superconformal Chern-Simons theory was proposed as gauge theory dual to Type IIA string theory on AdS4*CP3. We study integrability of the theory from conformal dimension spectrum of single trace operators at planar limit. At strong `t Hooft coupling, the spectrum is obtained from excitation energy of free superstring on OSp(6|2,2)/SO(3,1)xSU(3)xU(1) supercoset. We recall that the worldsheet theory is integrable classically by utilizing well-known results concerning sigma model on symmetric space. With R-symmetry group SU(4), we also solve relevant Yang-Baxter equation for a spin chain system associated with the single trace operators. From the solution, we construct alternating spin chain Hamiltonian involving three-site interactions between 4 and 4*. At weak `t Hooft coupling, we study gauge theory perturbatively, and calculate action of dilatation operator to single trace operators up to two loops. To ensure consistency, we computed all relevant Feynman diagrams contributing to the dilatation opeator. We find that resulting spin chain Hamiltonian matches with the Hamiltonian derived from Yang-Baxter equation. We further study new issues arising from the shortest gauge invariant operators transforming as 15 and 1 under SU(4). We observe that `wrapping interactions' are present, compute the true spectrum and find that the spectrum agrees with prediction from supersymmetry. We also find that scaling dimension computed naively from alternating spin chain Hamiltonian coincides with the true spectrum. We solve Bethe ansatz equations for small number of excitations, and find indications of correlation between excitations of 4's and 4*'s and of nonexistence of mesonic (4 4*) bound-state.