Algebraic Curves for Integrable String Backgrounds
K. Zarembo
TL;DR
The paper analyzes integrable string backgrounds within AdS/CFT by developing a unified finite-gap framework for coset sigma-models. It derives classical Bethe equations and associated algebraic curves for a broad set of AdS backgrounds (including AdS_5×S^5, AdS_4×CP^3, and multiple AdS_2/AdS_3 variants) using Z_4 symmetric cosets and their Lax formulations. A key result is the explicit construction of density-based integral equations (and their Dynkin-diagram structure) that encode the semiclassical string spectrum and map onto quantum Bethe equations via thermodynamic limits, with connections to the S-matrix and BES dressing phase. The work extends known finite-gap methods beyond AdS_5×S^5, offering a systematic route to semiclassical spectra in diverse RR backgrounds and highlighting the role of inversion symmetries and central (energy-carrying) nodes in the underlying integrable structures.
Abstract
Many Ramond-Ramond backgrounds which arise in the AdS/CFT correspondence are described by integrable sigma-models. The equations of motion for classical spinning strings in these backgrounds are exactly solvable by finite-gap integration techniques. We review the finite-gap integral equations and algebraic curves for coset sigma-models, and then apply the results to the AdS(d+1) backgrounds with d=4,3,2,1.
