B-mode polarization in Einstein-aether theory

Journal Article · Sat Oct 15 04:00:00 EDT 2011 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.84.084051· OSTI ID:21607934

Nakashima, Masahiro ^[1]; Kobayashi, Tsutomu ^[2]

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1. Department of Physics, Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan)
2. Research Center for the Early Universe (RESCEU), Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan)

We study how the dynamical vector degree of freedom in modified gravity affects the CMB B-mode polarization in terms of the Einstein-aether theory. In this theory, vector perturbations can be generated from inflation, which can grow on superhorizon scales in the subsequent epochs and thereby leaves imprints on the CMB B-mode polarization. We derive the linear perturbation equations in a covariant formalism, and compute the CMB B-mode polarization using the CAMB code modified so as to incorporate the effect of the aether vector field. We find that the amplitude of the B-mode signal from the aether field can be larger than the contribution from the inflationary gravitational waves for reasonable initial conditions and for a viable range of model parameters, in which perturbation modes propagate superluminally. We also give an analytic argument explaining the shape of the spectrum based on the tight coupling approximation.

• OSTI ID: 21607934
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 8 Vol. 84; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
APPROXIMATIONS
CALCULATION METHODS
COUPLING
DEGREES OF FREEDOM
DISTURBANCES
ELECTROMAGNETIC RADIATION
FIELD THEORIES
GENERAL RELATIVITY THEORY
GRAVITATION
GRAVITATIONAL WAVES
MICROWAVE RADIATION
PERTURBATION THEORY
POLARIZATION
RADIATIONS
RELATIVITY THEORY
RELICT RADIATION
SPECTRA
VECTOR FIELDS