Massive particle pair production and oscillation in Friedman Universe: reheating energy and entropy, and cold dark matter

She-Sheng Xue

doi:10.1140/epjc/s10052-023-11524-9

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2023) 83: 355
https://doi.org/10.1140/epjc/s10052-023-11524-9

Regular Article - Theoretical Physics

Massive particle pair production and oscillation in Friedman Universe: reheating energy and entropy, and cold dark matter

She-Sheng Xue¹^,2^,3^,4^a

¹ ICRANet Piazzale della Repubblica, 10, 65122, Pescara, Italy
² Physics Department, Sapienza University of Rome, Rome, Italy
³ INFN, Sezione di Perugia, Perugia, Italy
⁴ ICTP-AP, University of Chinese Academy of Sciences, Beijing, China

^a xue@icra.it, shesheng.xue@gmail.com

Received: 11 January 2023
Accepted: 16 April 2023
Published online: 3 May 2023

Abstract

Suppose that the early Universe starts with a cosmological $Λ$ $\Lambda$ -term (dark energy) originating from quantum spacetime at the Planck scale. Dark energy drives inflation and reheating by reducing its value for massive particle–antiparticle pairs production and oscillation, resulting in a holographic and massive pair plasma state. The back-and-forth reaction of dark energy and massive pairs slows inflation to its end and starts reheating by rapidly producing stable and unstable pairs. We introduce the Boltzmann-type rate equation describing the back-and-forth reaction. It forms a close set with Friedman equations and reheating equations for unstable pairs decay to relativistic particles. The numerical solutions show preheating, massive pairs dominated and genuine reheating episodes. We obtain the reheating temperature and entropy in terms of the tensor-to-scalar ratio $0 < r < 0.047$ $$0< r < 0.047$$ consistently with observations. Stable massive pairs represent cold dark matter particles and weakly interact with dark energy. The resultant cold dark matter abundance $Ω_{c} \sim 10^{- 1}$ $\Omega _c\sim 10^{-1}$ is about a constant in time.

© The Author(s) 2023

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