Minimal Higgs inflation with an $R^2$ term in Palatini gravity

Abstract

It has recently been suggested that the Standard Model Higgs boson could act as the inflaton while minimally coupled to gravity - given that the gravity sector is extended with an $\alpha R^2$ term and the underlying theory of gravity is of Palatini, rather than metric, type. In this paper, we revisit the idea and correct some shortcomings in earlier studies. We find that in this setup the Higgs can indeed act as the inflaton and that the tree-level predictions of the model for the spectral index and the tensor-to-scalar ratio are $n_s\simeq 0.941$, $r\simeq 0.3/(1+10^{-8}\alpha )$, respectively, for a typical number of e-folds, $N=50$, between horizon exit of the pivot scale $k=0.05{\mathrm{Mpc}}^{-1}$ and the end of inflation. Even though the tensor-to-scalar ratio is suppressed compared to the usual minimally coupled case and can be made compatible with data for large enough $\alpha$, the result for $n_s$ is in severe tension with the Planck results. We briefly discuss extensions of the model.

6 pages, 1 figure, 1 table. v2: Important modifications, results partly changed. v3: Minor modifications, matches the version accepted for publication in Phys. Rev. D

References in corpus (10)

• The Standard Model Higgs boson as the inflaton
• Inflation with Non-Minimal Coupling: Metric vs. Palatini Formulations
• Higgs-Palatini Inflation and Unitarity
• Higgs G-inflation
• Higgs inflation with loop corrections in the Palatini formulation
• Running Kinetic Inflation
• Metric-affine Gravity and Inflation
• Resurrecting Quadratic Inflation with a non-minimal coupling to gravity
• Coleman-Weinberg linear inflation: metric vs. Palatini formulation
• Inflationary Perturbations in Palatini Generalised Gravity

Cited by in corpus (38)

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• Equivalence of inflationary models between the metric and Palatini formulation of scalar-tensor theories
• Inflation in Metric-Affine Quadratic Gravity
• Coupling Metric-Affine Gravity to a Higgs-Like Scalar Field
• Tachyonic Preheating in Palatini $R^2$ Inflation
• Palatini $R^2$ Quintessential Inflation
• Implications of Palatini gravity for inflation and beyond
• Scalaron-Higgs inflation reloaded: Higgs-dependent scalaron mass and primordial black hole dark matter
• On UV-completion of Palatini-Higgs inflation
• Slow-roll inflation in Palatini $F(R)$ gravity
• Coupling Metric-Affine Gravity to the Standard Model and Dark Matter Fermions
• On the number of $e$-folds in the Jordan and Einstein frames
• Multiple point criticality principle and Coleman-Weinberg inflation
• Inflation in Weyl-invariant Einstein-Cartan gravity
• 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
• Inflation and reheating in quadratic metric-affine gravity with derivative couplings
• Cosmological constraints of Palatini $f(\mathcal{R})$ gravity
• Issues in Palatini ${\mathcal{R}}^2$ inflation: Bounds on the Reheating Temperature
• Quintessential Inflation in Palatini Gravity
• First constraints on non-minimally coupled Natural and Coleman-Weinberg inflation and massive neutrino self-interactions with Planck+BICEP/Keck
• Beyond (and back to) Palatini quadratic gravity and inflation
• Freeze-In of radiative keV-scale neutrino dark matter from a new $\text{U}(1{)}_{\text{B-L}}$
• $\tilde{\xi }$-attractors in metric-affine gravity
• General Einstein-Cartan quadratic gravity with derivative couplings
• Hybrid metric-Palatini Higgs inflation
• Palatini Higgs and Coleman-Weinberg inflation with non-minimal coupling
• Inflation in Symmergent Metric-Palatini Gravity
• Natural inflation in Palatini $F(R,X)$
• Toward a gravitational network: Bridging metric-affine gravity and no-scale supergravity
• $\beta$-function reconstruction of Palatini inflationary attractors
• Gravitational waves during Higgs inflation from complex geometrical scalar-tensor theory of gravity
• Inflationary assessment of $F(\mathcal{R},\tilde{\mathcal{R}})$ Einstein-Cartan models
• Scalar-Induced Gravitational Waves in Palatini $f(R)$ Gravity
• Large Field Polynomial Inflation in Palatini $f(R,\varphi )$ Gravity