RST model

The Russo–Susskind–Thorlacius model[1] or RST model in short is a modification of the CGHS model to take care of conformal anomalies and render it analytically soluble.

In the CGHS model, if we include Faddeev–Popov ghosts to gauge-fix diffeomorphisms in the conformal gauge, they contribute an anomaly of -24.

Each matter field contributes an anomaly of 1.

To the CGHS action is added, where κ is either

In the conformal gauge, It might appear as if the theory is local in the conformal gauge, but this overlooks the fact that the Raychaudhuri equations are still nonlocal.