1998/09/17 by Eduardo Guendelman, E. I. Guendelman, Guendelman, E. I. +3
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Theory (hep-th) #Relativity and Gravitational Theory #gr-qc #hep-th
paper · pdf · doi:10.48550/arxiv.gr-qc/9809052
Plenary talk given by E.I.Guendelman in the Fourth Alexander Friedmann International Seminar on Gravitation and Cosmology, St. Petersburg, 1998; 25 pages. LaTeX
arxiv created 1998/09/17 · openalex publication_date 1998/09/17 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study field theory models in the context of a gravitational theory based on the requirement that the measure of integration in the action is not necessarily √(-g) but it is determined dynamically through additional degrees of freedom, like four scalar fields ϕa. We study three possibilities for the general structure of the theory: (A) The total action has the form S=∫ΦLd4x where the measure Φis built from the scalars ϕa in such a way that the transformation L→ L+const does not effect equations of motion. Then an infinite dimensional shifts group of the measure fields (SGMF) ϕa by arbitrary functions of the Lagrangian density L is a symmetry group of the action. (B) The total action has the form S=S1+S2, S1=∫ΦL1d4x, S2=∫√(-g)L2d4x which is the only model different from (A) and invariant under SGMF (but now with fa= fa(L1)). Similarly, now only S1 satisfies the requirement that the transformation L1→ L1+const does not effect equations of motion. Both in the case (A) and in the case (B) it is assumed that L, L1, L2 do not depend on ϕa. (C) The action includes a term which breaks the SGMF symmetry. It is shown that in the first order formalism in cases (A) and (B) the CCP is solved: the effective potential vanishes in a true vacuum state (TVS) without fine tuning. In the case (C), the breaking of the SGMF symmetry induces a nonzero energy density for the TVS.