Strings in Horizons, Dissipation and a Possible Interpretation of the Hagedorn Temperature

TL;DR

This paper explores the behavior of closed bosonic strings near horizons, identifying a critical temperature akin to the Hagedorn temperature, which impacts their thermal equilibrium and offers insights into horizon microstructure.

Contribution

It introduces a semiclassical approach linking string entanglement at horizons with a critical temperature similar to the Hagedorn temperature, suggesting new interpretations of horizon microstructure.

Findings

Existence of a critical temperature for string thermal equilibrium.

Critical temperature magnitude aligns with the Hagedorn temperature.

Partition function becomes ill-defined above this temperature.

Abstract

We consider the entanglement of closed bosonic strings intersecting the event horizon of a Rindler spacetime and, by using some simplified (rather semiclassical) arguments and some elements of the string field theory, we show the existence of a critical temperature beyond which closed strings \emph{cannot be in thermal equilibrium}. The order of magnitude of this critical value coincides with the Hagedorn temperature, which suggests an interpretation consistent with the fact of having a partition function which is bad defined for temperatures higher than it. Possible implications of the present approach on the microscopical structure of stretched horizons are also pointed out.