PRINCIPLE OF NONGRAVITATING VACUUM ENERGY AND SOME OF ITS CONSEQUENCES

For Einstein's a general relativity (GR) or the alternatives suggested up to date, the vacuum energy gravitates. We present a model where a new measure is introduced for integration of the total action in D-dim ensional spacetime. This measure is built from D scalar fields phi(a). As a consequence of such a choice of the measure, the matter Lagrangi an L(m) can be changed by adding a constant while no gravitational eff ects, such as a cosmological term, are induced. Such a nongravitating vacuum energy theory has infinite dimensional symmetry group which con tains volume-preserving diffeomorphisms in the internal space of scala r fields phi(a). Other symmetries contained in this symmetry group sug gest a deep connection of this theory with theories of extended object s. In general the theory is different from GR although for certain cho ices of L(m), which are related to the existence of an additional symm etry, solutions of GR are solutions of the model. This is achieved in four dimensions if L(m) is due to fundamental bosonic and fermionic st rings. Other types of matter where this feature of the theory is reali zed, are, for example, scalars without potential or subjected to nonli near constraints, massless fermions, and point particles. The point pa rticle plays a special role, since it is a good phenomenological descr iption of matter at large distances. de Sitter Space is realized in an unconventional way, where the de Sitter metric holds, but such de Sit ter space is supported by the existence of a variable scalar field whi ch in practice destroys the maximal symmetry. The only spacetime where maximal symmetry is not broken, in a dynamical sense, is Minkowski sp ace. The theory has nontrivial dynamics in 1 + 1 dimensions, unlike GR .