📝 SummarXiv

Abstract

Two-dimensional dilaton gravity provides a valuable framework to study the dynamics of quantum black holes. These models are often coupled to conformal scalar fields, which capture essential quantum effects such as the trace anomaly, while remaining analytically tractable. From the viewpoint of two-dimensional quantum field theory, unitary theories require a positive central charge. However, theories with a total negative central charge naturally arise from the contribution of the Faddeev-Popov ghosts to the effective action. Recent analyses of the Callan-Giddins-Harvey-Strominger (CGHS) model with a Russo-Susskin-Thorlacius (RST) counterterm have shown that a negative central charge can remove curvature singularities in the backreacted geometry. In this work, we argue that singularity resolution arises from the negative central charge itself, rather than the particular dynamics of a given model. To support this, we present analogous results in spherically reduced Einstein gravity.