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Title: Pre-inflationary clues from String Theory?

''Brane supersymmetry breaking'' occurs in String Theory when the only available combinations of D-branes and orientifolds are not mutually BPS and yet do not introduce tree-level tachyon instabilities. It is characterized by the emergence of a steep exponential potential, and thus by the absence of maximally symmetric vacua. The corresponding low-energy supergravity admits intriguing spatially-flat cosmological solutions where a scalar field is forced to climb up toward the steep potential after an initial singularity, and additional milder terms can inject an inflationary phase during the ensuing descent. We show that, in the resulting power spectra of scalar perturbations, an infrared suppression is typically followed by a pre-inflationary peak that reflects the end of the climbing phase and can lie well apart from the approximately scale invariant profile. A first look at WMAP9 raw data shows that, while the χ{sup 2} fits for the low-ℓ CMB angular power spectrum are clearly compatible with an almost scale invariant behavior, they display nonetheless an eye-catching preference for this type of setting within a perturbative string regime.
Authors:
 [1] ;  [2]
  1. Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397 JAPAN (Japan)
  2. Scuola Normale Superiore and INFN, Piazza dei Cavalieri, 7, Pisa, 56126 (Italy)
Publication Date:
OSTI Identifier:
22373660
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 04; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; COSMOLOGICAL INFLATION; D-BRANES; MATHEMATICAL SOLUTIONS; PERTURBATION THEORY; POTENTIALS; SCALAR FIELDS; SINGULARITY; STRING MODELS; STRING THEORY; SUPERGRAVITY; SYMMETRY BREAKING