2007/07/31 by Masao Iihoshi, Sergei V. Ketov
Physics and Astronomy · #Astrophysics #Black Holes and Theoretical Physics #Classical mechanics #Cosmology #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Gravitation #Graviton #Massive gravity #Mathematical physics #Physics #Superstring theory #Supersymmetry #Theoretical physics #gr-qc #hep-th
paper · pdf · doi:10.1155/2008/521389
published as Adv.High Energy Phys.2008:521389,2008 · 33 pages, LaTeX, no figures; extensive revision, Sec.6 and references added, stability analysis included
openalex publication_date 2008/01/01 · arxiv created 2008/09/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We review the status of the fourth‐order (quartic in the spacetime curvature) terms induced by superstrings/M‐theory (compactified on a warped torus) in the leading order with respect to the Regge slope parameter, and study their (nonperturbative) impact on the evolution of the Hubble scale in the context of the four‐dimensional FRW cosmology. After taking into account the quantum ambiguities in the definition of the off‐shell superstring effective action, we propose the generalized Friedmann equations, find the existence of their (de Sitter) exact inflationary solutions without a spacetime singularity, and constrain the ambiguities by demanding stability and the scale factor duality invariance of our solutions. The most naive (Bel‐Robinson tensor squared) quartic terms are ruled out, thus giving the evidence for the necessity of extra quartic (Ricci tensor‐dependent) terms in the off‐shell gravitational effective action for superstrings. Our methods are generalizable to the higher orders in the spacetime curvature.