Positivity bounds on reconstructed Horndeski models

Abstract

Positivity bounds provide conditions that a consistent UV-completion exists for a quantum field theory. We examine their application to Horndeski gravity models reconstructed from the effective field theory (EFT) of dark energy. This enables us to assess whether particular phenomenological parameterizations of the EFT functions reconstruct theories that respect or violate the positivity bounds. We find that commonly adopted EFT parametrizations, cast in terms of the dark energy density or power laws of the scale factor, only satisfy the positivity bounds in non-trivial regions of the parameter space. We then examine parameterizations of the inherently stable EFT basis, constructed to avoid gradient and ghost instabilities by default. In stark contrast, in this basis the positivity bounds either only provide constraints in a-priori unrealistic regions of the parameter space or do not provide any constraints on parameter values at all. The application of positivity bounds to common parametrizations of the standard EFT functions can therefore lead to artificial conclusions that the region of viable Horndeski modifications of gravity is highly constrained. Our results provide a strong motivation, in addition to the default avoidance of theoretical instabilities, for instead adopting parametrizations of the inherently stable EFT basis when testing dark energy and modified gravity models with forthcoming cosmological survey data.

arXiv comment11 pages, 3 figures

References in corpus (53)

• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• LSST: from Science Drivers to Reference Design and Anticipated Data Products
• The Dynamics of General Relativity
• Beyond the Cosmological Standard Model
• Generalized G-inflation: Inflation with the most general second-order field equations
• From k-essence to generalised Galileons
• Causality, Analyticity and an IR Obstruction to UV Completion
• Dark Energy after GW170817: dead ends and the road ahead
• Everything You Always Wanted To Know About The Cosmological Constant Problem (But Were Afraid To Ask)
• Strong constraints on cosmological gravity from GW170817 and GRB 170817A
• Dark Energy after GW170817 and GRB170817A
• Implications of the Neutron Star Merger GW170817 for Cosmological Scalar-Tensor Theories
• Healthy theories beyond Horndeski
• Degenerate higher derivative theories beyond Horndeski: evading the Ostrogradski instability
• The Effective Field Theory of Dark Energy
• Dark Energy vs. Modified Gravity
• Maximal freedom at minimum cost: linear large-scale structure in general modifications of gravity
• Essential Building Blocks of Dark Energy
• Planck 2015 results. XIV. Dark energy and modified gravity
• Breaking a Dark Degeneracy with Gravitational Waves
• Dark Energy or Modified Gravity? An Effective Field Theory Approach
• Challenges to Self-Acceleration in Modified Gravity from Gravitational Waves and Large-Scale Structure
• The Effective Theory of Quintessence: the w<-1 Side Unveiled
• Gravitational Rainbows: LIGO and Dark Energy at its Cutoff
• Energy's and amplitudes' positivity
• A unifying description of dark energy
• Effective Field Theory of Dark Energy: a Review
• Positivity Bounds for Scalar Theories
• hi_class: Horndeski in the Cosmic Linear Anisotropy Solving System
• Beyond Amplitudes' Positivity and the Fate of Massive Gravity
• Amplitudes' Positivity, Weak Gravity Conjecture, and Modified Gravity
• Gravitational Wave Decay into Dark Energy
• Signs of Analyticity in Single-Field Inflation
• A Simplified Approach to General Scalar-Tensor Theories
• Weakly Broken Galileon Symmetry
• Symmetries, Sum Rules and Constraints on Effective Field Theories
• Constraints on deviations from $\Lambda$CDM within Horndeski gravity
• A Unified Approach to Cosmic Acceleration
• Dark energy after GW170817, revisited
• Dark-Energy Instabilities induced by Gravitational Waves
• Positivity in the sky
• A general theory of linear cosmological perturbations: scalar-tensor and vector-tensor theories
• The effective field theory of inflation/dark energy and the Horndeski theory
• A Class of Effective Field Theory Models of Cosmic Acceleration
• Gravitational wave constraints on dark sector models
• Finding Horndeski theories with Einstein gravity limits
• Reconstructing Horndeski theories from phenomenological modified gravity and dark energy models on cosmological scales
• Reconstructing Horndeski models from the effective field theory of dark energy
• Classifying Linearly Shielded Modified Gravity Models in Effective Field Theory
• Inherently stable effective field theory for dark energy and modified gravity
• Screening and degenerate kinetic self-acceleration from the nonlinear freedom of reconstructed Horndeski theories

Cited by in corpus (8)

• Positivity Bounds on Dark Energy: When Matter Matters
• Positivity Bounds without Boosts
• Scalar Fields Near Compact Objects: Resummation versus UV Completion
• Parameterised post-Newtonian formalism for the effective field theory of dark energy via screened reconstructed Horndeski theories
• On tachyonic stability priors for dark energy
• Theoretical priors in scalar-tensor cosmologies: Shift-symmetric Horndeski models
• Dark energy constraints in light of theoretical priors
• Propagator positivity bounds for cosmological correlators