U.S. - Uruguay Cooperative Research: Knot Theory and the Dynamics of Quantum Gravity

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9811610PullinThis Americas Program award will support a collaborative research project on quantum gravity between Dr. Jorge Pullin, the Pennsylvania State University and Dr. Rodolfo Gambini, Universidad de la Republica, Montevideo, Uruguay. The research will deal with nonperturbative quantization of general relativity using connection and loop techniques. In particular, they wish to explore the definition of a Hamiltonian constraint in terms of the use of the loop derivative, and find physical states for the theory that would be annihilated by all constraints.An important question to be addressed by this study is the role that the cosmological constant plays in the space of states of the theory. Up to now, they have found that states with a cosmological constant are framing-dependent knot invariants, whereas states without a cosmological constant are framing-independent. Whether this is a generic behavior or is confined to certain states only, will be investigated.The approach of both groups to the subject is complementary. The approach combines the background in general relativity and gravitational physics of the researchers at Penn State with the expertise of the Montevideo group in particle physics. ***