Adiabatic and entropy perturbations from inflation
By C. Gordon, D. Wands, Bruce A. Bassett, R. Maartens. 2000
721 citations recorded by the source corpus.
We study adiabatic ~curvature! and entropy ~isocurvature! perturbations produced during a period of cosmological inflation that is driven by multiple scalar fields with an arbitrary interaction potential. A local rotation in field space is performed to separate out the adiabatic and entropy modes. The resulting field equations show explicitly how on large scales entropy perturbations can source adiabatic perturbations if the background solution follows a curved trajectory in field space, and how adiabatic perturbations cannot source entropy perturbations in the long-wavelength limit. It is the effective mass of the entropy field that determines the amplitude of entropy perturbations during inflation. We present two applications of the equations. First, we show why one in general expects the adiabatic and entropy perturbations to be correlated at the end of inflation, and calculate the cross correlation in the context of a double inflation model with two non-interacting fields. Second, we consider two-field preheating after inflation, examining conditions under which entropy perturbations can alter the large-scale curvature perturbation and showing how our new formalism has advantages in numerical stability when the background solution follows a non-trivial trajectory in field space.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/436d079bdaa2d7eba53ffb2c07183fa4fc605026
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Citations in the corpus
- Features of heavy physics in the CMB power spectrum (2010, methodology): “We can also compute the power spectrum for isocurvature modes and cross correlation as [36, 62, 63]”
- Generating PBHs and small-scale GWs in two-field models of inflation (2020, methodology): “We would refer the reader to our earlier paper [43] as well as the original efforts for further details in this regard [32, 51–54].”
- Inflation, Cosmic Perturbations and Non-Gaussianities (2013, methodology): “We can rotate the basis in the field space of those fields, such that there is only one rolling field [168, 169].”
- New Ekpyrotic Cosmology (2007, neutral): “(In covariant form, the NEC is the requirement that T n n 0 for any null vector [48].”