B-mode polarization in Einstein-aether theory
- Department of Physics, Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan)
- 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, Vol. 84, Issue 8; Other Information: DOI: 10.1103/PhysRevD.84.084051; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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