AdS $N$-body problem at large spin
Petr Kravchuk, Jeremy A. Mann
TL;DR
This work establishes a semiclassical Berezin-Toeplitz quantization framework for leading-twist $N$-body states in AdS at large spin $J$, revealing a classical phase space given by $\mathrm{Gr}_{+}(2,N)$ (or ${\mathbb{C}P}^{N-2}$ after reduction) and an effective Hamiltonian encoding pairwise interactions. For $N=3$, the spectrum is controlled by Bohr-Sommerfeld quantization with acute/obtuse regions, and subleading corrections yield harmonic-oscillator-like towers for low-lying states, with permutation symmetries imposing detailed degeneracy structures. For general $N$, the problem remains semiclassical but with $N-2$ degrees of freedom, producing Weyl-law density of states and localized low-lying excitations around a unique minimum; BT quantization and pseudodifferential methods characterize the leading and subleading spectra, while numerical diagonalization confirms the analytic predictions and the Lorentzian inversion formula connections. The results provide analytical handles on multi-twist operator spectra in holographic CFTs, illuminate connections to LLL physics on hyperbolic spaces, and suggest avenues toward understanding universal multi-twist dynamics beyond holography. Overall, the paper bridges AdS/CFT, geometric quantization, and spectral analysis to reveal the structure of high-spin, multi-particle sectors in strongly coupled quantum field theories.
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.
