Oscillating scalar fields in extended quintessence

Abstract

We study a rapidly-oscillating scalar field with potential $V(\varphi )=k|\varphi {|}^n$ nonminally coupled to the Ricci scalar $R$ via a term of the form $(1-8\pi G_0\xi {\varphi }^2)R$ in the action. In the weak coupling limit, we calculate the effect of the nonminimal coupling on the time-averaged equation of state parameter $\gamma =(p+\rho )/\rho$. The change in $⟨\gamma ⟩$ is always negative for $n\ge 2$ and always positive for $n<0.71$ (which includes the case where the oscillating scalar field could serve as dark energy), while it can be either positive or negative for intermediate values of $n$. Constraints on the time-variation of $G$ force this change to be infinitesimally small at the present time whenever the scalar field dominates the expansion, but constraints in the early universe are not as stringent. The rapid oscillation induced in $G$ also produces an additional contribution to the Friedman equation that behaves like an effective energy density with a stiff equation of state, but we show that, under reasonable assumptions, this effective energy density is always smaller than the density of the scalar field itself.

14 pages

References in corpus (28)

• The Confrontation between General Relativity and Experiment
• The Ekpyrotic Universe: Colliding Branes and the Origin of the Hot Big Bang
• Scaling solutions in general non-minimal coupling theories
• A classification of scalar field potentials with cosmological scaling solutions
• A New Cosmological Model of Quintessence and Dark Matter
• Cosmological scaling solutions of non-minimally coupled scalar fields
• Extended Quintessence
• A New Nucleosynthesis Constraint on the Variation of G
• Self-similar cosmological solutions with a non-minimally coupled scalar field
• Tracking Extended Quintessence
• The response of primordial abundances to a general modification of $G_{\mathrm{N}}$ and/or of the early universe expansion rate
• Dynamical and Gravitational Instability of Oscillating-Field Dark Energy and Dark Matter
• The Cyclic Model Simplified
• Constraints on the Variation of G from Primordial Nucleosynthesis
• Evolution of cosmological perturbations in a stage dominated by an oscillatory scalar field
• Equation of State of Oscillating Brans-Dicke Scalar and Extra Dimensions
• Extended quintessence and the primordial helium abundance
• Extended Quintessence and its Late-time Domination
• High frequency oscillations of Newton's constant induced by inflation
• Evolution of Oscillating Scalar Fields as Dark Energy
• Oscillatory inflation in non-minimal derivative coupling model
• Fitting Non-Minimally Coupled Scalar Models to Gold SnIa Dataset
• Scalar Field Oscillations Contributing to Dark Energy
• Scalar-tensor cosmologies with a potential in the general relativity limit: time evolution
• Scalar-tensor cosmologies with dust matter in the general relativity limit
• Rapid Oscillatory quintessence with variable equation of state parameter in non minimal derivative coupling model
• Does the Newton's gravitational constant vary sinusoidally with time? Orbital motions say no
• Cosmology of Nonlinear Oscillations

Cited by in corpus (6)

• Selected topics in scalar-tensor theories and beyond
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• Cosmic acceleration in screening hybrid quintessence model
• No scalar hair in nonminimal derivative coupling model for Neumann and Dirichlet reflecting star