Equivalence Principle in Chameleon Models

Abstract

Most theories that predict time and/or space variation of fundamental constants also predict violations of the Weak Equivalence Principle. In 2004 Khoury and Weltman proposed the so called chameleon field arguing that it could help avoiding experimental bounds on the WEP while having a non-trivial cosmological impact. In this paper we revisit the extent to which these expectations continue to hold as we enter the regime of high precision tests. The basis of the study is the development of a new method for computing the force between two massive bodies induced by the chameleon field which takes into account the influence on the field by both, the large and the test bodies. We confirm that in the thin shell regime the force does depend non-trivially on the test body\' s composition, even when the chameleon coupling constants are universal. We also propose a simple criterion based on energy minimization, that we use to determine which of the approximations used in computing the scalar field in a two body problem is better in each specific regime. As an application of our analysis we then compare the resulting differential acceleration of two test bodies with the corresponding bounds obtained from Eötvös type experiments. We consider two setups: 1) an Earth based experiment where the test bodies are made of Be and Al; 2) the Lunar Laser Ranging experiment. We find that for some choices of the free parameters of the chameleon model the predictions of the Eötvös parameter are larger than some of the previous estimates. As a consequence, we put new constrains on these free parameters. An important result of our analysis is that our approach leads to new constraints on the parameter space of the chameleon models.

42 pages, 15 figures Accepted for publication in PRD

References in corpus (22)

• The Confrontation between General Relativity and Experiment
• Models of f(R) Cosmic Acceleration that Evade Solar-System Tests
• Test of the Equivalence Principle Using a Rotating Torsion Balance
• Constraining f(R) Gravity as a Scalar Tensor Theory
• Evading Equivalence Principle Violations, Cosmological and other Experimental Constraints in Scalar Field Theories with a Strong Coupling to Matter
• f(R) Gravity and Chameleon Theories
• Atom-interferometry constraints on dark energy
• Solar system and equivalence principle constraints on f(R) gravity by chameleon approach
• Equivalence Principle Implications of Modified Gravity Models
• Gravity Resonance Spectroscopy Constrains Dark Energy and Dark Matter Scenarios
• Detecting Chameleons through Casimir Force Measurements
• Probing Dark Energy with Atom Interferometry
• A Compendium of Chameleon Constraints
• Chameleon Dark Energy and Atom Interferometry
• The XMM Cluster Survey: Testing chameleon gravity using the profiles of clusters
• Atomic Precision Tests and Light Scalar Couplings
• Chameleon dark energy models with characteristic signatures
• Revisiting chameleon gravity - thin-shells and no-shells with appropriate boundary conditions
• Unscreening Modified Gravity in the Matter Power Spectrum
• Status of MICROSCOPE, a mission to test the Equivalence Principle in space
• Probing Modified Gravity with Atom-Interferometry: a Numerical Approach
• Equivalence principle in scalar-tensor gravity

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• Precision Gravity Tests and the Einstein Equivalence Principle
• Screened Scalar Fields in the Laboratory and the Solar System
• Dilaton Solutions for Laboratory Constraints and Lunar Laser Ranging
• A general study of chameleon fifth force in gravity space experiments
• Solar System tests and chameleon effect in f (R) gravity
• New test on the Einstein equivalence principle through the photon ring of black holes
• Fifth force induced by a chameleon field on nested cylinders
• Constraining Chameleon screening using galaxy cluster dynamics
• Constraining massless dilaton theory at Solar system scales with the planetary ephemeris INPOP
• Thick shell regime in the chameleon two-body problem
• Solar system tests and neutron stars in $f(R)$ gravity revisited
• Caustic and hydrostatic mass bias: Implications for modified gravity
• What to expect from scalar-tensor space geodesy
• Cosmological and lunar laser ranging constraints on evolving dark energy in a nonminimally coupled curvature-matter gravity model