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arXiv · 2505.06420

The spectrum of pure dS$_3$ gravity in the static patch

Joydeep Chakravarty·Alexander Maloney·Keivan Namjou·Simon F. Ross
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Abstract

We consider the quantum mechanical description of the de Sitter static patch in three-dimensional general relativity. We consider a Lorentzian path integral that conjecturally computes the Fourier transform of the spectrum of the static patch Hamiltonian. We regulate a saddle point for this integral by a complex deformation that connects it to future infinity. Our computation is thus closely connected with the wave function of de Sitter gravity on a torus at future infinity. Motivated by this, we identify an infinite number of saddle points that contribute to our Lorentzian path integral. Their sum gives a surprisingly simple result, which agrees with the expected features of the de Sitter static patch. For example, the thermal entropy, evaluated at the de Sitter temperature, agrees with the Bekenstein-Hawking formula. We also obtain a spectrum in the spin-zero sector, which is bounded, discrete, and has an integer degeneracy of states. It includes a dense spectrum of states, making both positive and negative contributions to the trace, arranged in such a way that negative contributions are invisible in the computation of any smooth observable. Nevertheless, several mysteries remain.

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Joydeep Chakravarty, Alexander Maloney, Keivan Namjou, Simon F. Ross. 2025-05-09. The spectrum of pure dS$_3$ gravity in the static patch. https://arxiv.org/abs/2505.06420

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