The scaling function at strong coupling from the quantum string Bethe equations

TL;DR

This paper investigates the strong coupling behavior of the scaling function related to large spin operators in N=4 super Yang-Mills theory using string Bethe Ansatz equations, confirming predictions with semiclassical string results.

Contribution

It provides a detailed analysis of the string Bethe equations at strong coupling, including the Eden-Staudacher equation with the Arutyunov-Frolov-Staudacher phase, and confirms the unique solution aligns with string theory predictions.

Findings

Recovered semiclassical results for short strings

Analyzed the strong coupling Eden-Staudacher equation

Confirmed the unique solution matches string theory predictions

Abstract

We study at strong coupling the scaling function describing the large spin anomalous dimension of twist two operators in ${\cal N}=4$ super Yang-Mills theory. In the spirit of AdS/CFT duality, it is possible to extract it from the string Bethe Ansatz equations in the $\mathfrak{sl}(2)$ sector of the $\ads$ superstring. To this aim, we present a detailed analysis of the Bethe equations by numerical and analytical methods. We recover several short string semiclassical results as a check. In the more difficult case of the long string limit providing the scaling function, we analyze the strong coupling version of the Eden-Staudacher equation, including the Arutyunov-Frolov-Staudacher phase. We prove that it admits a unique solution, at least in perturbation theory, leading to the correct prediction consistent with semiclassical string calculations.