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Title: Nonperturbative instabilities as a solution of the cosmological moduli problem

Abstract

It is widely accepted that moduli in the mass range 10 eV-10{sup 4} GeV which start to oscillate with an amplitude of the order of the Planck scale either jeopardize successful predictions of nucleosynthesis or overclose the Universe. It is shown that the moduli problem can be relaxed by making use of parametric resonance. A new nonperturbative decay channel for moduli oscillations is discussed. This channel becomes effective when the oscillating field results in a net negative mass term for the decay products. This scenario allows for the decay of the moduli much before nucleosynthesis and, therefore, leads to a complete solution of the cosmological moduli problem.

Authors:
;  [1]
  1. Department of Physics, McGill University, Montreal, QC, H3A 2T8 (Canada)
Publication Date:
OSTI Identifier:
20776736
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 73; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevD.73.043519; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; AMPLITUDES; COSMOLOGY; DECAY; GEV RANGE; INSTABILITY; MATHEMATICAL SOLUTIONS; NEGATIVE MASS; NUCLEOSYNTHESIS; OSCILLATIONS; RESONANCE; UNIVERSE

Citation Formats

Shuhmaher, Natalia, and Brandenberger, Robert. Nonperturbative instabilities as a solution of the cosmological moduli problem. United States: N. p., 2006. Web. doi:10.1103/PhysRevD.73.043519.
Shuhmaher, Natalia, & Brandenberger, Robert. Nonperturbative instabilities as a solution of the cosmological moduli problem. United States. doi:10.1103/PhysRevD.73.043519.
Shuhmaher, Natalia, and Brandenberger, Robert. Wed . "Nonperturbative instabilities as a solution of the cosmological moduli problem". United States. doi:10.1103/PhysRevD.73.043519.
@article{osti_20776736,
title = {Nonperturbative instabilities as a solution of the cosmological moduli problem},
author = {Shuhmaher, Natalia and Brandenberger, Robert},
abstractNote = {It is widely accepted that moduli in the mass range 10 eV-10{sup 4} GeV which start to oscillate with an amplitude of the order of the Planck scale either jeopardize successful predictions of nucleosynthesis or overclose the Universe. It is shown that the moduli problem can be relaxed by making use of parametric resonance. A new nonperturbative decay channel for moduli oscillations is discussed. This channel becomes effective when the oscillating field results in a net negative mass term for the decay products. This scenario allows for the decay of the moduli much before nucleosynthesis and, therefore, leads to a complete solution of the cosmological moduli problem.},
doi = {10.1103/PhysRevD.73.043519},
journal = {Physical Review. D, Particles Fields},
number = 4,
volume = 73,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2006},
month = {Wed Feb 15 00:00:00 EST 2006}
}
  • We review scenarios that have been proposed to solve the cosmological problem caused by moduli in string theory, the postmodern Polonyi problem (PPP). In particular, we discuss the difficulties encountered by the apparently ``trivial`` solution of this problem, in which moduli masses are assumed to arise from nonperturbative, SUSY-preserving, dynamics at a scale higher than that of SUSY breaking. This suggests a powerful {ital cosmological} {ital vacuum} {ital selection} {ital principle} in superstring theory. However, we argue that if one eschews the possibility of cancellations between different exponentials of the inverse string coupling, the mechanism described above cannot stabilize themore » dilaton. Thus, even if supersymmetric dynamics gives mass to the other moduli in string theory, the dilaton mass must be generated by SUSY breaking, and dilaton domination of the energy density of the Universe cannot be avoided. We conclude that the only proposal for solving the PPP that works is the intermediate scale inflation scenario of Randall and Thomas. However, we point out that all extant models have ignored unavoidably large inhomogeneities in the cosmological moduli density at very early times, and speculate that the effects associated with nonlinear gravitational collapse of these inhomogeneities may serve as an efficient mechanism for converting moduli into ordinary matter. As an important by-product of this investigation we show that in a postinflationary universe minima of the effective potential with a negative cosmological constant are not stationary points of the classical equations of scalar field cosmology. Instead, such points lead to catastrophic gravitational collapse of that part of the Universe which is attracted to them. Thus postinflationary cosmology dynamically chooses non-negative values of the cosmological constant. This implies that supersymmetry {ital must} be broken in any sensible inflationary cosmology. (Abstract Truncated)« less
  • Typically the moduli fields acquire mass {ital m}{sub {phi}}{sup 2}={plus_minus}{ital C}{sup 2}{ital H}{sup 2} in the early universe, which shifts the position of the minimum of their effective potential and leads to an excessively large energy density of the oscillating moduli fields at the later stages of the evolution of the universe. This constitutes the cosmological moduli problem, or Polonyi field problem. We show that the cosmological moduli problem can be solved or at least significantly relaxed in the theories in which {ital C}{gt}1, as well as in some models with {ital C}{lt}1. {copyright} {ital 1996 The American Physical Society.}
  • Recently, an interesting class of direct gauge mediation supersymmetry (SUSY) breaking models were proposed, in which the minimum of the potential of the SUSY breaking field was determined by the inverted hierarchy mechanism. We consider their cosmological implications. In this class of models, the SUSY breaking field has a very flat potential, which may have cosmological importance. Assuming the initial amplitude of the SUSY breaking field to be of the order of the Planck scale, it can be a source of large entropy production. Special attention is paid to the cosmological moduli problem, and we will see that the cosmologicalmore » mass density of the moduli field can be significantly reduced. {copyright} {ital 1998} {ital The American Physical Society}« less
  • Recently, an interesting class of the direct gauge mediation supersymmetry (SUSY) breaking models are proposed, in which the minimum of the potential of the SUSY breaking field is determined by the inverted hierarchy mechanism. We consider their cosmological implications. In this class of models, SUSY breaking field has a very flat potential, which may have a cosmological importance. Assuming the initial amplitude of the SUSY breaking field to be of the order of the Planck scale, it can be a source of a large entropy production. A special attention is paid to the cosmological moduli problem, and we will seemore » the cosmological mass density of the moduli field can be significantly reduced.« less
  • It is shown that the coherent field oscillation of moduli fields with weak or TeV scale masses can dissipate its energy efficiently if they have a derivative coupling to standard bosonic fields in a thermal state. This mechanism provides a new solution to the cosmological moduli problem without creating too much entropy at late time.