A New Look at the RST Model Jian-Ge Zhoua, F. Zimmerschieda, J
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server A new lo ok at the RST mo del a a a,b Jian-Ge Zhou , F. Zimmerschied , J.{Q. Liang and a H. J. W. Muller{Ki rsten a Department of Physics, University of Kaiserslautern, P. O. Box 3049, D{67653 Kaiserslautern, Germany b Institute of Theoretical Physics, Shanxi University Taiyuan, Shanxi 030006, P. R. China and Institute of Physics, Academia Sinica, Beijing 100080, P. R. China Abstract The RST mo del is augmented by the addition of a scalar eld and a b oundary term so that it is well-p osed and lo cal. Expressing the RST action in terms of the ADM formulation, the constraint structure can b e analysed completely.It is shown that from the view p oint of lo cal eld theories, there exists a hidden dynamical eld in the RST mo del. Thanks to the presence of this hidden 1 dynamical eld, we can reconstruct the closed algebra of the constraints which guarantee the general invariance of the RST action. The resulting stress tensors T are recovered to b e true tensor quantities. Esp ecially, the part of the stress tensors for the hidden dynamical eld gives the precise expression for t . 1 At the quantum level, the cancellation condition for the total central charge is reexamined. Finally, with the help of the hidden dynamical eld , the fact 1 that the semi-classical static solution of the RST mo del has two indep endent parameters (P,M), whereas for the classical CGHS mo del there is only one, can b e explained.
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