2019/10/07 by She-Sheng Xue, Xue, She-Sheng · 1 citation
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #gr-qc #hep-th
paper · pdf · doi:10.48550/arxiv.1910.03938
We add discussions on the non-exponentially suppressed number density of massive pairs produced nonadiabatically, in connection with the pioneering work by Chung, Kolb and Riotto, Phys. Rev. D 59, 023501 (1998), arXiv:hep-ph/980223
arxiv created 2021/04/25 · arxiv updated 2021/04/27
Suppose that the early Universe starts with a quantum spacetime originated cosmological Λ-term at the Planck scale M\rm pl. The cosmological energy density ρ_Λ drives inflation and simultaneously reduces its value to create the matter-energy density ρ_M via the continuous pair productions of massive fermions and antifermions. The decreasing ρ_Λ and increasing ρ_M, in turn, slows down the inflation to its end when the pair production rate ΓM is larger than the Hubble rate H. The density ρ_Λ and Hubble rate H are uniquely determined by two independent equations from the Einstein equation and energy conservation law, besides the ρ_M is determined by pair productions. As a result, inflation naturally appears and theoretical results agree with Planck 2018 observations. Suppose that the reheating efficiently converts ρ_Λ to ρ_M≫ ρ_Λ accounting for the most relevant Universe mass, and some massive pairs decay to relativistic particles of energy density ρ_R starting the hot Big Bang. The back reaction ρ_M↔ H↔ ρ_Λ is weak but continues. As a consequence, ρΛ closely tracks down ρR from the reheating end up to the radiation-matter equilibrium, then it varies very slowly, ρΛ∝ constant, due to the transition from radiation dominant epoch to matter dominant epoch. Therefore the cosmic coincidence problem can be possibly avoided.