Imprints of massive primordial fields on large-scale structure

Journal Article · Mon Feb 01 04:00:00 EST 2016 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2016/02/017· OSTI ID:22525020

Dimastrogiovanni, Emanuela ^[1]; Fasiello, Matteo ^[2]; Kamionkowski, Marc ^[3]

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1. Department of Physics and School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 85827-1404 (United States)
2. Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, Stanford, CA, 94306 (United States)
3. Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218 (United States)

Attention has focussed recently on models of inflation that involve a second or more fields with a mass near the inflationary Hubble parameter H, as may occur in supersymmetric theories if the supersymmetry-breaking scale is not far from H. Quasi-single-field (QsF) inflation is a relatively simple family of phenomenological models that serve as a proxy for theories with additional fields with masses m∼ H. Since QsF inflation involves fields in addition to the inflaton, the consistency conditions between correlations that arise in single-clock inflation are not necessarily satisfied. As a result, correlation functions in the squeezed limit may be larger than in single-field inflation. Scalar non-Gaussianities mediated by the massive isocurvature field in QsF have been shown to be potentially observable. These are especially interesting since they would convey information about the mass of the isocurvature field. Here we consider non-Gaussian correlators involving tensor modes and their observational signatures. A physical correlation between a (long-wavelength) tensor mode and two scalar modes (tss), for instance, may give rise to local departures from statistical isotropy or, in other words, a non-trivial four-point function. The presence of the tensor mode may moreover be inferred geometrically from the shape dependence of the four-point function. We compute tss and stt (one soft curvature mode and two hard tensors) bispectra in QsF inflation, identifying the conditions necessary for these to 'violate' the consistency relations. We find that while consistency conditions are violated by stt correlations, they are preserved by the tss in the minimal QsF model. Our study of primordial correlators which include gravitons in seeking imprints of additional fields with masses m∼ H during inflation can be seen as complementary to the recent ''cosmological collider physics'' proposal.

• OSTI ID: 22525020
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 02 Vol. 2016; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CORRELATION FUNCTIONS
CORRELATIONS
COSMOLOGICAL INFLATION
GRAVITONS
INFLATIONARY UNIVERSE
ISOTROPY
MASS
POTENTIALS
SCALARS
SUPERSYMMETRY
SYMMETRY BREAKING
TENSORS
WAVELENGTHS