Weyl Invariance and Black Hole Evaporation

TL;DR

This paper explores Weyl invariance in 2D dilaton gravity models, showing how it relates to Hawking radiation and black hole evaporation, and connects to the RST model through a non-local metric redefinition.

Contribution

It demonstrates the equivalence of Weyl-invariant effective actions to the RST model, providing a new approach to solving semiclassical black hole equations.

Findings

Weyl invariance converts the trace anomaly into the Virasoro anomaly.

Covariance can be restored via a non-local metric redefinition.

The approach yields solutions consistent with the RST model.

Abstract

We consider the semiclassical dynamics of CGHS black holes with a Weyl-invariant effective action for conformal matter. The trace anomaly of Polyakov effective action is converted into the Virasoro anomaly thus leading to the same flux of Hawking radiation. The covariance of semiclassical equations can be restored through a non-local redefinition of the metric-dilaton fields. The resulting theory turns out to be equivalent to the RST model. This provides a mechanism to solve semiclassical equations of 2D dilaton gravity coupled to conformal matter for classically soluble models.