Dynamical Relaxation of the Cosmological Constant and Matter Creation in the Universe

Abstract

In this Letter we discuss the issues of the graceful exit from inflation and of matter creation in the context of a recent scenario \cite{RHBrev} in which the back-reaction of long wavelength cosmological perturbations induces a negative contribution to the cosmological constant and leads to a dynamical relaxation of the bare cosmological constant. The initially large cosmological constant gives rise to primordial inflation, during which cosmological perturbations are stretched beyond the Hubble radius. The cumulative effect of the long wavelength fluctuations back-reacts on the background geometry in a form which corresponds to the addition of a negative effective cosmological constant to the energy-momentum tensor. In the absence of an effective scalar field driving inflation, whose decay can reheat the Universe, the challenge is to find a mechanism which produces matter at the end of the relaxation process. In this Letter, we point out that the decay of a condensate representing the order parameter for a ``flat'' direction in the field theory moduli space can naturally provide a matter generation mechanism. The order parameter is displaced from its vacuum value by thermal or quantum fluctuations, it is frozen until the Hubble constant drops to a sufficiently low value, and then begins to oscillate about its ground state. During the period of oscillation it can decay into Standard Model particles similar to how the inflaton decays in scalar-field-driven models of inflation.

6 pages

References in corpus (8)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• Cosmological consequences of MSSM flat directions
• Adiabatic density perturbations and matter generation from the MSSM
• MSSM flat direction as a curvaton
• MSSM Higgses as the source of reheating and all matter
• Sneutrino condensate source for density perturbations, leptogenesis and low reheat temperature
• A model for fluctuating inflaton coupling: (s)neutrino induced adiabatic perturbations and non-thermal leptogenesis
• CMB constraints on non-thermal leptogenesis

Cited by in corpus (16)

• One-loop corrections to the curvature perturbation from inflation
• One-loop corrections to a scalar field during inflation
• Avoidance of Big Rip In Phantom Cosmology by Gravitational Back Reaction
• Constraints on backreaction in dust universes
• Correlated isocurvature perturbations from mixed inflaton-curvaton decay
• A Measure of Cosmological Acceleration
• Dynamical instability of fluid spheres in the presence of a cosmological constant
• Possible Constraints on the Duration of Inflationary Expansion from Quantum Stress Tensor Fluctuations
• Growth index and statefinder diagnostic of Oscillating Dark Energy
• Irreversible thermodynamical description of warm inflationary cosmological models
• Can universe exit from phantom inflation due to gravitational back reaction?
• Sneutrino condensate as a candidate for the hot big bang cosmology
• Dark Energy: The Observational Challenge
• Loop Corrections to Cosmological Perturbations in Multi-field Inflationary Models
• Dark Energy From Dynamical Projective Connections
• The VECRO hypothesis