Ghost-free infinite-derivative dilaton gravity in two dimensions

TL;DR

This paper develops ghost-free infinite-derivative extensions of two-dimensional gravity theories, specifically SRG and CGHS, providing non-local modifications to classical solutions and ensuring the absence of ghosts.

Contribution

It introduces ghost-free infinite-derivative modifications for SRG and CGHS theories, extending classical solutions while maintaining stability and consistency.

Findings

Constructed ghost-free infinite-derivative SRG and CGHS models.

Derived non-local modifications to Schwarzschild and CGHS black-hole solutions.

Ensured ghost-free property in the extended theories.

Abstract

We present the ghost-free infinite-derivative extensions of the Spherically-Reduced Gravity (SRG) and Callan-Giddings-Harvey-Strominger (CGHS) theories in two space-time dimensions. For the case of SRG, we specify the Schwarzschild-type gauge and diagonalise the quadratic action for field perturbations after taking the background fields to be those of the flat-space solution with a linear dilaton. Using the obtained diagonalisation, we construct ghost-free infinite-derivative modifications of the SRG theory. In the context of this modified SRG theory we derive a non-local modification of the linearised spherically-reduced Schwarzschild solution. For the case of CGHS gravity, we work in the conformal gauge and diagonalise the quadratic action associated with this theory for a general background solution. Using these results, we construct the ghost-free infinite-derivative modifications of the CGHS theory and examine non-local modifications to the linearised CGHS black-hole solution.