Advances in the theory of strong gravity

This is concerned with how ideas normally only encountered in the context of gravity may be relevant to hadron physics. In such models the spacetime metric to which hadrons respond (the strong metric) is different from that experienced by leptons (the weak metric). First there is a short review of the f-g theory of Isham, Salam and Strathdee, and Wess and Zumino. Then a class of exact, spherically symmetric, classical solutions of the coupled f-g field equations is found. The f and g metrics each effectively induce a cosmological constant in the field equations of the other with the result that the solutions involve de Sitter and anti-de Sitter spacetimes. An investigation into the existence of sensible quantum field theories follows. The usual quantisation procedures are inapplicable to anti-de Sitter spacetime but a consistent quantisation scheme can be devised. A model is presented in which the strong and weak metrics are conformally related by a scalar field, based on an adaption of the Brans-Dicke scalar-tensor theory of gravity. One consequence of the model concerns quark interaction. Finally a few remarks are made concerning the future development of strong gravity theories. (author)