Modified gravity models for inflation: In conformity with observations

Abstract

We consider a modified gravity framework for inflation by adding to the Einstein-Hilbert action a direct $f(\varphi )T$ term, where $\varphi$ is identified as the inflaton and $T$ is the trace of the energy-momentum tensor. The framework goes to Einstein gravity naturally when the inflaton decays out. We investigate inflation dynamics in this $f(\varphi )T$ gravity (not to be confused with torsion-scalar coupled theories) on a general basis and then apply it to three well-motivated inflationary models. We find that the predictions for the spectral tilt and the tensor-to-scalar ratio are sensitive to this new $f(\varphi )T$ term. This $f(\varphi )T$ gravity brings chaotic and natural inflation into better agreement with data and allows a larger tensor-to-scalar ratio in the Starobinsky model.

arXiv comment16 pages, 3 figures. Match the version accepted for publication in PRD

References in corpus (37)

• Extended Theories of Gravity
• Introduction to Modified Gravity and Gravitational Alternative for Dark Energy
• f(R,T) gravity
• Modified Gravity Theories on a Nutshell: Inflation, Bounce and Late-time Evolution
• Planck 2018 results. X. Constraints on inflation
• Particle Physics Models of Inflation and the Cosmological Density Perturbation
• Modified teleparallel gravity: inflation without inflaton
• Encyclopaedia Inflationaris
• Inflation Dynamics and Reheating
• Extra force in $f(R)$ modified theories of gravity
• Class of viable modified $f(R)$ gravities describing inflation and the onset of accelerated expansion
• Natural Inflation: Particle Physics Models, Power Law Spectra for Large Scale Structure, and Constraints from COBE
• Unifying inflation with LambdaCDM epoch in modified f(R) gravity consistent with Solar System tests
• Natural Chaotic Inflation in Supergravity
• Dark Energy Dominance and Cosmic Acceleration in First Order Formalism
• Gravity assisted dark energy dominance and cosmic acceleration
• "Teleparallel" Dark Energy
• Monopoles as Big as a Universe
• Inflation in $f(R,\varphi )$-theories and mimetic gravity scenario
• Inflationary universe from perfect fluid and $F(R)$ gravity and its comparison with observational data
• Scaling attractors in interacting teleparallel dark energy
• Cosmological dynamics of tachyonic teleparallel dark energy
• Impact of neutrino properties on the estimation of inflationary parameters from current and future observations
• Modified gravity from the quantum part of the metric
• Inflationary Perturbations in No-Scale Theories
• Cosmological implications of modified gravity induced by quantum metric fluctuations
• Slow-roll inflation in f(R,T) gravity and a modified Starobinsky-like inflationary model
• Inflation in $f(R,T)$ Gravity
• Quasi-Conformal Models and the Early Universe
• Dimensional Transmutation in Gravity and Cosmology
• Natural inflation with a nonminimal coupling to gravity
• On the Viability of the Intermediate Inflation Scenario with $F(T)$ Gravity
• Inflation from a nonlinear magnetic monopole field nonminimally coupled to curvature
• Warm-assisted natural inflation
• Cascading dust inflation in Born-Infeld gravity
• Natural-Scalaron Inflation
• Modified Teleparallel Gravity induced by quantum fluctuations

Cited by in corpus (11)

• Finite-time Cosmological Singularities and the Possible Fate of the Universe
• Cosmological Inflation in f(Q, T) Gravity
• Slow-roll inflation in $f(R,T)$ gravity with a $RT$ mixing term
• Testing scale-invariant inflation against cosmological data
• Reheating constraints on modified single-field Natural Inflation models
• Tsallis holographic inflation in $f(R,T)$ gravity: CMB constraints, reheating, and swampland implications
• Inflation with antisymmetric tensor field: new candidates
• The Inflationary Quartic Hilltop Model in a Modified Gravity and Its Comparison with the Observations
• $F(\varphi )T$-Gravity and Inflationary Natural Model
• Scalar and vector modes in inflation with antisymmetric tensor field
• Slow-roll Hilltop Inflation in $f(\varphi ,T)$ gravity