Bulg. J. Phys. vol.42 no.3 (2015), pp. 249-262

Metric-Independent Volume-Forms in Gravity and Cosmology

E. Guendelman1, E. Nissimov2, S. Pacheva2
1Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
2Institute of Nuclear Research and Nuclear Energy, Bulgarian Acadademy of Sciences, 72 Tsarigradsko Chaussee, BG-1784 Sofia, Bulgaria
Abstract. Employing alternative spacetime volume-forms (generally-covariant integration measure densities) independent of the pertinent Riemannian spacetime metric have profound impact in general relativity. Although formally appearing as "pure-gauge" dynamical degrees of freedom they trigger a number of remarkable physically important phenomena such as: (i) new mechanism of dynamical generation of cosmological constant; (ii) new type of "quintessential inflation" scenario in cosmology; (iii) non-singular initial "emergent universe" phase of cosmological evolution preceding the inflationary phase; (iv) new mechanism of dynamical spontaneous breakdown of supersymmetry in supergravity; (v) gravitational electrovacuum "bags". We study in some detail the properties, together with their canonical Hamiltonian formulation, of a class of generalized gravity-matter models built with two independent non-Riemannian volume-forms and discuss their implications in cosmology.

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