Flat space cosmologies in two dimensions - Phase transitions and asymptotic mass-domination

TL;DR

This paper investigates phase transitions and thermodynamics of flat space cosmologies in two dimensions, introducing a new counterterm and analyzing asymptotic mass-domination, extending previous models and generalizing thermodynamic properties.

Contribution

It introduces a new dilaton-dependent counterterm for 2D flat space cosmologies and explores phase transitions and thermodynamics in asymptotically mass-dominated models.

Findings

Identified a phase transition between hot flat space and flat space cosmologies.

Derived a new counterterm for the Euclidean partition function.

Generalized thermodynamic analysis to asymptotically mass-dominated models.

Abstract

We study flat space cosmologies in two dimensions by taking the flat space limit of the Achucarro-Ortiz model. We unravel a phase transition between hot flat space and flat space cosmologies, and derive a new dilaton-dependent counterterm required for the consistency of the Euclidean partition function. Our results generalize to asymptotically mass-dominated 2-dimensional dilaton gravity models, whose thermodynamical properties we discuss. The novel case of asymptotic mass-domination is neither covered by the comprehensive discussion of hep-th/0703230 nor by the more recent generalization to dilaton gravity with confining U(1) charges in 1406.7007.