Dynamical Volume Element in Scale-Invariant and Supergravity Theories

Understand

The use in the action integral of a volume element of the form $\Phi d^{D}x$, where $\Phi$ is a metric-independent measure density, can yield new interesting results in all types of known generally coordinate-invariant theories: (1) 4-D theories of gravity plus matter fields; (2) reparametrization invariant theories of extended objects (strings and branes); (3) supergravity theories.

• In case (1) we obtain interesting insights concerning the cosmological constant problem, inflation and quintessence without the fifth force problem.
• In case (2) the above formalism leads to dynamically induced tension and to string models of non-abelian confinement.
• In case (3), we show that the modified-measure supergravity generates an arbitrary dynamically induced cosmological constant, i.e., a new mechanism of dynamical supersymmetry breaking.