Structure Constants in $\mathcal{N}=4$ SYM at Finite Coupling as Worldsheet $g$-Function

TL;DR

This paper introduces a nonperturbative integrability-based method to compute three-point functions involving determinant operators in planar N=4 SYM, revealing a determinant structure and a connection to worldsheet g-functions, with extensive tests at various couplings.

Contribution

It develops a novel nonperturbative approach using TBA to compute structure constants involving determinant operators, extending integrability techniques to finite coupling.

Findings

Derived a determinant structure for correlators involving determinants.

Established a nonperturbative finite-coupling boundary state and g-function.

Validated results through extensive weak and strong coupling tests.

Abstract

We develop a novel nonperturbative approach to a class of three-point functions in planar $\mathcal{N}=4$ SYM based on Thermodynamic Bethe Ansatz (TBA). More specifically, we study three-point functions of a non-BPS single-trace operator and two determinant operators dual to maximal Giant Graviton D-branes in AdS$_5\times$S$^{5}$. They correspond to disk one-point functions on the worldsheet and admit a simpler and more powerful integrability description than the standard single-trace three-point functions. We first introduce two new methods to efficiently compute such correlators at weak coupling; one based on large $N$ collective fields, which provides an example of open-closed-open duality discussed by Gopakumar, and the other based on combinatorics. The results so obtained exhibit a simple determinant structure and indicate that the correlator can be interpreted as a generalization of $g$-functions in 2d QFT; an overlap between an integrable boundary state and a state corresponding to the single-trace operator. We then determine the boundary state at finite coupling using the symmetry, the crossing equation and the boundary Yang-Baxter equation. With the resulting boundary state, we derive the ground-state $g$-function based on TBA and conjecture its generalization to other states. This is the first fully nonperturbative proposal for the structure constants of operators of finite length. The results are tested extensively at weak and strong couplings. Finally, we point out that determinant operators can provide better probes of sub-AdS locality than single-trace operators and discuss possible applications.