On Thermodynamical Properties of Some Coset CFT Backgrounds

TL;DR

This paper explores the thermodynamical properties of specific string theory backgrounds with multiple asymptotic regions, revealing complex temperature structures and the absence of a Hartle-Hawking analog.

Contribution

It provides new insights into the Euclidean versions and thermodynamics of charged black holes and Nappi-Witten cosmological models in string theory.

Findings

Multiple smooth Euclidean black hole solutions with different temperatures.

No direct analog of the Hartle-Hawking state for these backgrounds.

Non-isotropic temperature associated with the Nappi-Witten cosmology.

Abstract

We investigate the thermodynamical features of two Lorentzian signature backgrounds that arise in string theory as exact CFTs and possess more than two disconnected asymptotic regions: the 2-d charged black hole and the Nappi-Witten cosmological model. We find multiple smooth disconnected Euclidean versions of the charged black hole background. They are characterized by different temperatures and electro-chemical potentials. We show that there is no straightforward analog of the Hartle-Hawking state that would express these thermodynamical features. We also obtain multiple Euclidean versions of the Nappi-Witten cosmological model and study their singularity structure. It suggests to associate a non-isotropic temperature with this background.