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. 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. So, unless N=24, we will have gravitational anomalies. To the CGHS action

, the following term

is added, where κ is either or depending upon whether ghosts are considered. The nonlocal term leads to nonlocality. 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.

References

  1. Russo, Jorge; Susskind, Leonard; Thorlacius, Lárus (15 Oct 1992). "The Endpoint of Hawking Evaporation". Physical Review. D. 46 (8): 3444–3449. arXiv:hep-th/9206070. Bibcode:1992PhRvD..46.3444R. doi:10.1103/PhysRevD.46.3444. PMID 10015289.


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