Edge Modes on Stringy Horizons

TL;DR

This paper investigates edge modes on stringy horizons in de Sitter spacetime, deriving a modular invariant partition function that generalizes known gauge theory results to string theory, with implications for horizon microstates.

Contribution

It introduces a novel string theory partition function for edge modes near horizons, extending gauge theory edge contributions to the full string spectrum with UV finiteness.

Findings

Partition function expressed via Harish-Chandra character.

Modular invariant one-loop partition function derived.

Generalization of gauge theory edge contributions to string theory.

Abstract

For a quantum field of arbitrary mass and spin in the static patch of de Sitter spacetime, the Euclidean partition function receives contributions from edge modes localized on the horizon, expressible in terms of the Harish-Chandra character of the de Sitter group. Considering the flat limit and summing over all string fields, we obtain the partition function of edge modes in string theory near the Minkowski-Rindler horizon. Application of the Kronecker limit formula naturally yields a modular invariant one-loop partition function. The resulting expression generalizes the edge contribution of a massive vector boson in a spontaneously broken gauge theory to the infinite tower in string theory. It is naturally ultraviolet finite and amenable to a state-counting interpretation.