Abstract
The understanding of the primordial mechanism that seeded the cosmic structures we observe today in the sky is one of the major goals in cosmology. The leading paradigm for such a mechanism is provided by the inflationary scenario, a period of violent accelerated expansion in the very early stages of evolution of the universe. While our current knowledge of the physics of inflation is limited to phenomenological models which fit observations, an exquisite understanding of the particle content and interactions taking place during inflation would provide breakthroughs in our understanding of fundamental physics at high energies. In this review, we summarize recent theoretical progress in the modeling of the imprint of primordial interactions in the large-scale structures of the universe. We focus specifically on the effects of such interactions on the statistical distribution of dark-matter halos, providing a consistent treatment of the steps required to connect the correlations generated among fields during inflation all the way to the late-time correlations of halos.
Highlights
Cosmological observations reveal a universe filled with structures over a wide range of scales
Inflation is required by Cosmic Microwave Background (CMB) to run for O(60) e-folds [6] and as a consequence the Hubble parameter has to stay almost constant within a typical Hubble time H−1
We start by briefly introducing the basic points of the in-in formalism and connect it to the deviation from Gaussian statistics of the primordial perturbation ζ in Section 3.1, we review different types of interactions as produced by various models, or classes of models, of inflation in Section 3.2 and we conclude with remarks about the current status and future prospects of detection of primordial non-Gaussianity, Section 3.3
Summary
Cosmological observations reveal a universe filled with structures over a wide range of scales. Primordial perturbations provide the initial conditions with which matter overdensities grew under the effect of gravitational instability and formed all the structures in the universe It is, natural to hope to extract information about inflation by studying how matter is distributed in the universe. We want to summarize recent theoretical progress in the modeling of the imprint of primordial interactions, taking place during inflation, in the clustering of dark-matter halos. Even within the modeling of dark-matter halos, we will restrict mostly to the analytic treatment of the evolution of perturbations, from inflation all the way to the present universe, short paragraphs will be devoted to recent numerical progress in the study of structure formation. We will not investigate the three-point correlation function of halos (nor galaxies), which is a natural observable for primordial three-point functions
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