2003/10/30 by Wolung Lee, Li-Zhi Fang
Physics and Astronomy · #Adiabatic process #Anisotropy #Black Holes and Theoretical Physics #Cosmic microwave background #Cosmology and Gravitation Theories #Dissipation #Dissipative system #Galaxies: Formation, Evolution, Phenomena #Inflation (cosmology) #Inflaton #Physics #Quantum electrodynamics #Quantum mechanics #Scalar (mathematics) #Spectral density #Statistics #astro-ph
paper · pdf · doi:10.1103/physrevd.69.023514
published as Phys.Rev. D69 (2004) 023514 · 18 pages using revtex4, accepted for publication in PRD
arxiv created 2003/10/30 · openalex publication_date 2004/01/30 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate the primordial scalar perturbations in thermal dissipative inflation where the radiation component (thermal bath) persists and the density fluctuations are thermally originated. The perturbation generated in this model is hybrid; i.e., it consists of both adiabatic and isocurvature components. We calculate the fractional power ratio (S) and the correlation coefficient (cos\ensuremathΔ) between the adiabatic and the isocurvature perturbations at the commencing of the radiation regime. Since the adiabatic or isocurvature decomposition of hybrid perturbations generally is gauge dependent at superhorizon scales, when there is substantial energy exchange between the inflaton and the thermal bath, we carefully perform a proper decomposition of the perturbations. We find that the adiabatic and the isocurvature perturbations are correlated, even though the fluctuations of the radiation component are considered uncorrelated with that of the inflaton. We also show that both S and cos\ensuremathΔ depend mainly on the ratio between the dissipation coefficient \ensuremathΓ and the Hubble parameter H during inflation. The correlation is positive (cos\ensuremathΔ>0) for strong dissipation cases where \ensuremathΓ/H>0.2, and is negative for weak dissipation instances where \ensuremathΓ/H<0.2. Moreover, S and cos\ensuremathΔ in this model are not independent of each other. The predicted relation between S and cos\ensuremathΔ is consistent with the Wilkinson Microwave Anisotropy Probe observation. Other testable predictions are also discussed.