Non-gaussianities and the Stimulated creation of quanta in the inflationary universe

By Iván Agulló, L. Parker. 2010

163 citations recorded by the source corpus.

Cosmological inflation generates a spectrum of density perturbations that can seed the cosmic structures we observe today. These perturbations are usually computed as the result of the gravitationally-induced spontaneous creation of perturbations from an initial vacuum state. In this paper, we compute the perturbations arising from gravitationally-induced stimulated creation when perturbations are already present in the initial state. The effect of these initial perturbations is not diluted by inflation and survives to its end, and beyond. We consider a generic statistical density operator ρ describing an initial mixed state that includes probabilities for nonzero numbers of scalar perturbations to be present at early times during inflation. We analyze the primordial bispectrum for general configurations of the three different momentum vectors in its arguments. We find that the initial presence of quanta can significantly enhance non-gaussianities in the so-called squeezed limit. Our results show that an observation of non-gaussianities in the squeezed limit can occur for single-field inflation when the state in the very early inflationary universe is not the vacuum, but instead contains early-time perturbations. Valuable information about the initial state can then be obtained from observations of those non-gaussianities.

Subfields: Astronomy and Astrophysics, Finance

View Paper: https://www.semanticscholar.org/paper/22bb1588386591a966dec479794c2ea799061978

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In Astronomy and Astrophysics

1. D. Baumann
2. D. Green
3. E. Pajer
4. L. Senatore
5. S. Vagnozzi
6. M. Zaldarriaga
7. Guido D'Amico
8. V. Poulin

In Finance

1. D. Baumann
2. Abhay Ashtekar
3. V. Vennin
4. M. Liguori
5. V. Poulin
6. A. Starobinsky
7. P. Creminelli
8. J. Fergusson

Citations in the corpus

• Extension of the quantum theory of cosmological perturbations to the Planck era (2012, background): “[104] I.”
• The pre-inflationary dynamics of loop quantum cosmology: confronting quantum gravity with observations (2012, background): “This departure from the BD vacuum also has implications for the CMB and galaxy distribution [11–14] and observational tests for such effects have already been proposed [15–17].”
• Exploring cosmic origins with CORE: Inflation (2016, background): “On the other hand, a strongly enhanced signal in the squeezed limit is expected for a specific class of models, characterized by excited initial states [323, 324].”
• Loop quantum cosmology: a status report (2011, background): “Moreover, this departure from the Bunch-Davis vacuum has potential observable consequences in non-Gaussianities [225].”
• Symmetries and loops in inflation (2012, background): “Technically speaking, the authors of [44–47] do not claim to violate the consistency relation in the limit k → 0.”
• The (not so) squeezed limit of the primordial 3-point function (2011, background): “Another situation in which the consistency relation only holds asymptotically, for very large squeezing, is with modified vacuum states; see the discussion in [29].”