2010/10/27 by Ivan Agullo, Iván Agulló, Leonard Parker · 7 citations
Economics, Econometrics and Finance · Physics and Astronomy · #Bispectrum #Classical mechanics #Cosmic microwave background #Cosmological perturbation theory #Cosmology #Cosmology and Gravitation Theories #Dark energy #Galaxies: Formation, Evolution, Phenomena #Inflation (cosmology) #Inflationary epoch #Limit (mathematics) #Metric expansion of space #Non-Gaussianity #Physics #Primordial fluctuations #Quantum mechanics #Scalar (mathematics) #Scalar field #Spectral density #Stochastic processes and financial applications #Theoretical physics #Trispectrum #Universe #Vacuum state #astro-ph.CO #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.83.063526
published as Phys.Rev.D83:063526,2011 · 25 pages
arxiv created 2010/10/27 · openalex publication_date 2011/03/31 · arxiv updated 2015/03/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 \ensuremathρ 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.