Elementary Particles and Plasma in the First Hour of the Early Universe

Abstract

This work aims to deepen the understanding of the primordial composition of theUniverse in the temperature range 300 MeV > T > 0.02 MeV. In the following I exploit known properties of elementary particles and apply methods of kinetic theory and statistical physics to advance the understanding of the cosmic plasma. Within the Big Bang model the Universe began as a highly energetic fireball with an immensely high temperature and energy density. Consequently, an ultra-relativistic plasma was generated, exhibiting distinct properties as the Universe expanded and cooled. When the Universe is hot and dense, fundamental particles (such as quarks, leptons, and gauge bosons) play a crucial role in understanding the early Universe. These elementary particles were abundantly present once the temperature dropped below T = 130 GeV. Their interactions governed the dynamics of the early Universe. Our research focuses on investigation of these fundamental particles during the epoch which transits from primordial quark-gluon degrees of freedom to the era of normal matter plasma (H+, He+, e−). Our findings will offer valuable insights into the properties of the early Universe governing the properties of matter surrounding us today. In chapter 1 the properties of the Universe during the ‘first hour’ are described. I do not discuss diverse ideas about the origin of the Universe or how it emerged in thermal state. I begin with primordial Quark Gluon Plasma (QGP), continue to address the evolution of formed hadrons, of leptons, and the decoupling of neutrinos. I consider as well the stage where the electron-positron plasma is dominant. Most of these results depend on ambient (photon) temperature only. The standard cos- mological Friedmann-Lemaitre-Robertson-Walker (FLRW) model of the Universe is also introduced allowing the connection of the magnitude of temperature T to the age of the Universe t and the understanding of the speed of temperature change. I address in particular bottom and charm quarks near to the QGP transformation to hadrons (hadronization temperature TH = 150 MeV) in chapter 2. I examine the 19 relaxation time for the production and decay of bottom/charm quarks as a function of temperature from 300 MeV > T > 150 MeV. Of particular interest to me is that the bottom quarks are not in their chemical equilibrium. In chapter 3, I examine the strange particle composition of the expanding early Universe in the hadron epoch 150 MeV ≥ T ≥ 10 MeV, then investigate the freeze- out temperature for strangeness-producing by comparing the relevant reaction rates to the Hubble expansion rate and show that strangeness are kept in equilibrium via weak, electromagnetic, and strong interactions in the early Universe until T ≈ 13 MeV. In chapter 4, the matrix elements for neutrino coherent/incoherent scattering with matter and their application in early Universe are studied in detail. An overview of neutrino freeze-out process in early Universe is presented. After neu- trino freeze-out, I examine the relation between the effective number of neutrinos N eff ν and lepton asymmetry L in the Universe and its impact on Universe expansion. In chapter 5, I examine the dynamical picture of charged leptons μ± and e± in the early Universe and show that the persistence temperature for μ± in the early Universe is T = 4.2 MeV, and the e+ abundance can persist in the early Universe at relatively low value T ≈ 20 keV. Given the dense electron-positron plasma in the early Universe, I study the damping rate and investigate the magnetization process within dense electron-positron plasma in the early Universe. In chapter 6, I address the ongoing and prospective research projects intended for future publication including: The application of nonequilibrium bottom quark; Population of Higgs in the early Universe; Extra neutrino from microscopic processes after freeze-out; Self-consistent relaxation rate for electron-positron plasma. Finally, we summarize our important results and outlook for future study in chapter 7.