Magnetogenesis and the primordial non-gaussianity

Abstract

The primordial density fluctuation inevitably couples to all forms of matter via loop corrections and depends on the ambient conditions while inflation was ongoing. This gives us an opportunity to observe processes which were in progress while the universe was inflating, provided they were sufficiently dramatic to overcome suppression by powers of (H/MP)^2 ~ 10^(-9), where H is the Hubble scale during inflation and MP is the Planck mass. As an example, if a primordial magnetic field was synthesized during inflation, as suggested by some interpretations of the apparently universal 10^(-6) gauss field observed on galactic scales, then this could leave traces in inflationary observables. In this paper, I compute corrections to the spectrum and bispectrum generated by a varying electromagnetic coupling during inflation, assuming that the variation in this coupling is mediated by interaction with a collection of light scalar fields. If the mass scale associated with this interaction is too far below the Planck scale then the stability of perturbation theory can be upset. For the mass-scale which is relevant in the standard magnetogenesis scenario, however, the theory is stable and the model is apparently consistent with observational constraints.

37 pages, uses feynmp.sty and iopart.cls. v2: minor improvements in comparison with version submitted to (and accepted by) JCAP. Improves v1 with a more refined discussion of cutoffs and Lorentz invariance in Sections 4-5, but calculations are unchanged. Minor textual improvements throughout

References in corpus (19)

• Detection of primordial non-Gaussianity (fNL) in the WMAP 3-year data at above 99.5% confidence
• Stochastic Inflationary Scalar Electrodynamics
• Multi-brid inflation and non-Gaussianity
• Anisotropic Inflation from Vector Impurity
• New Experimental limit on Optical Photon Coupling to Neutral, Scalar Bosons
• Large non-Gaussianity from multi-brid inflation
• Classical approximation to quantum cosmological correlations
• Cosmology With Many Light Scalar Fields: Stochastic Inflation and Loop Corrections
• The curvature perturbation in a box
• Detecting Chameleons: The Astronomical Polarization Produced by Chameleon-like Scalar Fields
• On the Issue of the ζSeries Convergence and Loop Corrections in the Generation of Observable Primordial Non-Gaussianity in Slow-Roll Inflation. Part I: the Bispectrum
• Minimum Length Cutoff in Inflation and Uniqueness of the Action
• Testing Chameleon Theories with Light Propagating through a Magnetic Field
• Generation of Cosmological Seed Magnetic Fields from Inflation with Cutoff
• Simple Bounds from the Perturbative Regime of Inflation
• Active Galactic Nuclei Shed Light on Axion-like-Particles
• A search for chameleon particles using a photon regeneration technique
• Non-Gaussian Correlations Outside the Horizon
• Magnetogenesis from Cosmic String Loops