AdS $N$-body problem at large spin

TL;DR

This paper investigates the large spin limit of the N-body problem in Anti-de Sitter space, revealing a semiclassical structure linked to the positive Grassmannian and providing explicit spectral results for low-lying states.

Contribution

It introduces a semiclassical framework for the AdS N-body problem at large spin, connecting quantum states to classical geometry and explicitly quantizing the classical Hamiltonian.

Findings

Classical phase space identified with positive Grassmannian Gr_{+}(2,N)

Lowest excited states approximated by harmonic oscillators

Explicit energy expressions for low-lying states

Abstract

Motivated by the problem of multi-twist operators in general CFTs, we study the leading-twist states of the $N$-body problem in AdS at large spin $J$. We find that for the majority of states the effective quantum-mechanical problem becomes semiclassical with $\hbar=1/J$. The classical system at $J=\infty$ has $N-2$ degrees of freedom, and the classical phase space is identified with the positive Grassmannian $\mathrm{Gr}_{+}(2,N)$. The quantum problem is recovered via a Berezin-Toeplitz quantization of a classical Hamiltonian, which we describe explicitly. For $N=3$ the classical system has one degree of freedom and a detailed structure of the spectrum can be obtained from Bohr-Sommerfeld conditions. For all $N$, we show that the lowest excited states are approximated by a harmonic oscillator and find explicit expressions for their energies.