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Title: No fifth force in a scale invariant universe

Abstract

We revisit the possibility that the Planck mass is spontaneously generated in scale-invariant scalar-tensor theories of gravity, typically leading to a “dilaton.” The fifth force, arising from the dilaton, is severely constrained by astrophysical measurements. We explore the possibility that nature is fundamentally scale invariant and argue that, as a consequence, the fifth-force effects are dramatically suppressed and such models are viable. Finally, we discuss possible obstructions to maintaining scale invariance and how these might be resolved.

Authors:
ORCiD logo [1];  [2];  [1]
  1. Univ. of Oxford, Oxford (United Kingdom)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1350515
Alternate Identifier(s):
OSTI ID: 1347822
Report Number(s):
FERMILAB-PUB-16-665-T; arXiv:1612.03157
Journal ID: ISSN 2470-0010; PRVDAQ; 1502606; TRN: US1700605
Grant/Contract Number:
AC02-07CH11359
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 95; Journal Issue: 6; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Ferreira, Pedro G., Hill, Christopher T., and Ross, Graham G.. No fifth force in a scale invariant universe. United States: N. p., 2017. Web. doi:10.1103/PhysRevD.95.064038.
Ferreira, Pedro G., Hill, Christopher T., & Ross, Graham G.. No fifth force in a scale invariant universe. United States. doi:10.1103/PhysRevD.95.064038.
Ferreira, Pedro G., Hill, Christopher T., and Ross, Graham G.. Wed . "No fifth force in a scale invariant universe". United States. doi:10.1103/PhysRevD.95.064038. https://www.osti.gov/servlets/purl/1350515.
@article{osti_1350515,
title = {No fifth force in a scale invariant universe},
author = {Ferreira, Pedro G. and Hill, Christopher T. and Ross, Graham G.},
abstractNote = {We revisit the possibility that the Planck mass is spontaneously generated in scale-invariant scalar-tensor theories of gravity, typically leading to a “dilaton.” The fifth force, arising from the dilaton, is severely constrained by astrophysical measurements. We explore the possibility that nature is fundamentally scale invariant and argue that, as a consequence, the fifth-force effects are dramatically suppressed and such models are viable. Finally, we discuss possible obstructions to maintaining scale invariance and how these might be resolved.},
doi = {10.1103/PhysRevD.95.064038},
journal = {Physical Review D},
number = 6,
volume = 95,
place = {United States},
year = {Wed Mar 15 00:00:00 EDT 2017},
month = {Wed Mar 15 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
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  • Cited by 2
  • We investigate the general properties of expanding cosmological models which generate scale-invariant curvature perturbations in the presence of a variable speed of sound. We show that in an expanding universe, generation of a super-Hubble, nearly scale-invariant spectrum of perturbations over a range of wavelengths consistent with observation requires at least one of three conditions: (1) accelerating expansion, (2) a speed of sound faster than the speed of light, or (3) super-Planckian energy density.
  • A scale-invariant universe can have a period of accelerated expansion at early times: inflation. We use a frame-invariant approach to calculate inflationary observables in a scale invariant theory of gravity involving two scalar fields - the spectral indices, the tensor to scalar ratio, the level of isocurvature modes and non-Gaussianity. We show that scale symmetry leads to an exact cancellation of isocurvature modes and that, in the scale-symmetry broken phase, this theory is well described by a single scalar field theory. We find the predictions of this theory strongly compatible with current observations.
  • We present a new conformally invariant higher order operator on the n-dimensional sphere, acting on functions with values in the representation with highest weight ((5/2),(1/2),...,(1/2)). The construction uses the spectrum generating method by Branson, Orsted and Olafsson and is a higher spin analog of the construction of conformally invariant powers of Dirac operators by Liu and Ryan and of the operators on spin-forms constructed recently by Hong.