Inflationary Perturbations in Palatini Generalised Gravity

Abstract

We examine the generation of primordial perturbations during an inflationary epoch in generalised theories of gravity when the equations of motion are derived using the Palatini variational principle. Both f(R) and Scalar-Tensor theories are considered and we compare our results with those obtained under the conventional metric formalism. Non-linear generalisations of the action lead to different theories under the two variational choices and we obtain distinct results for scalar and tensor spectral indices and their ratio. We find the following general result; inflation driven solely by f(R) modifications alone do not result in suitable curvature perturbations whilst Scalar-Tensor theories generate nearly scalar invariant curvature perturbations but no tensor modes.

9 pages

References in corpus (32)

• f(R) Theories Of Gravity
• f(R) theories
• Introduction to Modified Gravity and Gravitational Alternative for Dark Energy
• Modified gravity with negative and positive powers of the curvature: unification of the inflation and of the cosmic acceleration
• The Standard Model Higgs boson as the inflaton
• Unifying phantom inflation with late-time acceleration: scalar phantom-non-phantom transition model and generalized holographic dark energy
• Extended Theories of Gravity and their Cosmological and Astrophysical Applications
• Class of viable modified $f(R)$ gravities describing inflation and the onset of accelerated expansion
• Cosmological viability of f(R)-gravity as an ideal fluid and its compatibility with a matter dominated phase
• A more accurate analytic calculation of the spectrum of cosmological perturbations produced during inflation
• Unifying inflation with LambdaCDM epoch in modified f(R) gravity consistent with Solar System tests
• Covariant conservation of energy momentum in modified gravities
• Inflation with Non-Minimal Coupling: Metric vs. Palatini Formulations
• Dark Energy: the equation of state description versus scalar-tensor or modified gravity
• Cosmological perturbations in the Palatini formulation of modified gravity
• Scalar-Tensor Models of Normal and Phantom Dark Energy
• The Universality of Einstein Equations
• Bouncing Cosmologies in Palatini $f(R)$ Gravity
• f(R) gravity theory and CMBR constraints
• Constraints from Inflation on Scalar-Tensor Gravity Theories
• Density perturbations in f(R) gravity theories in metric and Palatini formalisms
• Gauge-ready formulation of the cosmological kinetic theory in generalized gravity theories
• Inflationary spectra in generalized gravity: Unified forms
• Unification of inflation and cosmic acceleration in the Palatini formalism
• Unified Analysis of Cosmological Perturbations in Generalized Gravity
• Quantum fluctuations of Cosmological Perturbations in Generalized Gravity
• Metric-affine $f(R)$-gravity with torsion: an overview
• Non-Minimal Inflation Revisited
• Fourth-order gravity as the inflationary model revisited
• Slow-roll inflation in (R+R*4) gravity
• Bouncing Palatini cosmologies and their perturbations
• New Phenomenology for Palatini f(R) Theories: Non-singular Universes

Cited by in corpus (61)

• Higgs-Palatini Inflation and Unitarity
• Palatini inflation in models with an $R^2$ term
• Reheating in $R^2$ Palatini inflationary models
• Inflation and non-minimal scalar-curvature coupling in gravity and supergravity
• The Palatini side of inflationary attractors
• Minimal Higgs inflation with an $R^2$ term in Palatini gravity
• Coleman-Weinberg linear inflation: metric vs. Palatini formulation
• Rescuing Quartic and Natural Inflation in the Palatini Formalism
• Hidden Inflaton Dark Matter
• New universal attractor in nonmininally coupled gravity: Linear inflation
• Tracing the high energy theory of gravity: an introduction to Palatini inflation
• Palatini-Higgs inflation with non-minimal derivative coupling
• Scale-Invariant Quadratic Gravity and Inflation in the Palatini Formalism
• Attractor Behaviour in Multifield Inflation
• Palatini formulation of pure $R^2$ gravity yields Einstein gravity with no massless scalar
• Equivalence of inflationary models between the metric and Palatini formulation of scalar-tensor theories
• Palatini frames in scalar-tensor theories of gravity
• Scalar-metric-affine theories: Can we get ghost-free theories from symmetry?
• A simple $F(\mathcal{R},\varphi )$ deformation of Starobinsky inflationary model
• Chaotic inflation in modified gravitational theories
• Inflationary dynamics and preheating of the non-minimally coupled inflaton field in the metric and Palatini formalisms
• Axion dark matter from Higgs inflation with an intermediate $H_{\ast }$
• Reheating in Models with Non-minimal Coupling in metric and Palatini formalisms
• Palatini $R^2$ Quintessential Inflation
• Tachyonic Preheating in Palatini $R^2$ Inflation
• Cosmic acceleration from modified gravity with Palatini formalism
• Towards distinguishing variants of non-minimal inflation
• Implications of Palatini gravity for inflation and beyond
• Natural inflation with a nonminimal coupling to gravity
• Gravitational dark matter production in Palatini preheating
• Non-minimally coupled quartic inflation with Coleman-Weinberg one-loop corrections in the Palatini formulation
• Constant-roll in the Palatini-$R^2$ models
• Initial conditions for plateau inflation: a case study
• Slow-roll inflation in Palatini $F(R)$ gravity
• Minimal $k$-inflation in light of the conformal metric-affine geometry
• Quadratic, Higgs and hilltop potentials in the Palatini gravity
• Inflation and Reheating in f(R,h) theory formulated in the Palatini formalism
• New class of hybrid metric-Palatini scalar-tensor theories of gravity
• Non-minimal (self-)running inflation: metric vs. Palatini formulation
• General slow-roll inflation in $f(R)$ gravity under the Palatini approach
• Non-metric chaotic inflation
• On the number of $e$-folds in the Jordan and Einstein frames
• Variational approach to gravitational theories with two independent connections
• Multiple point criticality principle and Coleman-Weinberg inflation
• Extended interactions in the Palatini-$R^2$ inflation
• Constant-Roll Inflation in modified $f(R,\varphi )$ gravity model using Palatini Formalism
• Non-minimally coupled Natural Inflation: Palatini and Metric formalism with the recent BICEP/Keck
• Invariant quantities of Scalar-Tensor Theories for stellar structure
• Issues in Palatini ${\mathcal{R}}^2$ inflation: Bounds on the Reheating Temperature
• Quintessential Inflation in Palatini Gravity
• Beyond (and back to) Palatini quadratic gravity and inflation
• $\tilde{\xi }$-attractors in metric-affine gravity
• Non-minimal Higgs inflation within holographic cosmology
• Axion Quality Problem and Non-Minimal Gravitational Coupling in the Palatini Formulation
• Palatini Higgs and Coleman-Weinberg inflation with non-minimal coupling
• Natural inflation in Palatini $F(R,X)$
• Frame-Dependence of the Hamilton-Jacobi Formalism for Inflation and Reheating in Non-Minimal Gravity
• Observable predictions of generalised inflationary scenarios
• $\beta$-function reconstruction of Palatini inflationary attractors
• Non-linear effects in early Universe cosmology
• Scalar-Induced Gravitational Waves in Palatini $f(R)$ Gravity