Inflation from cosmological constant and nonminimally coupled scalar

Abstract

We consider inflation in a universe with a positive cosmological constant and a nonminimally coupled scalar field, in which the field couples both quadratically and quartically to the Ricci scalar. When considered in the Einstein frame and when the nonminimal couplings are negative, the field starts in slow roll and inflation ends with an asymptotic value of the principal slow roll parameter, ${\epsilon }_E=4/3$. Graceful exit can be achieved by suitably (tightly) coupling the scalar field to matter, such that at late time the total energy density reaches the scaling of matter, ${\epsilon }_E={\epsilon }_m$. Quite generically the model produces a red spectrum of scalar cosmological perturbations and a small amount of gravitational radiation. With a suitable choice of the nonminimal couplings, the spectral slope can be as large as $n_s\simeq 0.955$, which is about one standard deviation away from the central value measured by the Planck satellite. The model can be ruled out by future measurements if any of the following is observed: (a) the spectral index of scalar perturbations is $n_s>0.960$; (b) the amplitude of tensor perturbations is above about $r\sim 10^{-2}$; (c) the running of the spectral index of scalar perturbations is positive.

19 pages, 13 figures

References in corpus (7)

• Dynamics of dark energy
• The Confrontation between General Relativity and Experiment
• The Standard Model Higgs boson as the inflaton
• Gauge invariant cosmological perturbations for the nonminimally coupled inflaton field
• Late-time backreaction from inflationary fluctuations of a non-minimally coupled massless scalar
• Naturalness in Higgs inflation in a frame independent formalism
• Nonminimal coupling and the cosmological constant problem

Cited by in corpus (7)

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• Asymptotically Safe Non-Minimal Inflation
• A Graceful Exit for the Cosmological Constant Damping Scenario
• CMB power spectrum for emergent scenario and slow expansion in scalar-tensor theory of gravity
• Non-Minimal Inflation with a scalar-curvature mixing term $\frac{1}{2}\xi R{\varphi }^2$
• Topological inflation with graceful exit
• Testing an Inflation Model with Nonminimal Derivative Coupling in the Light of PLANCK 2015 Data