The Hubble parameter in the early universe with viscous QCD matter and finite cosmological constant
Abstract
The evolution of a flat, isotropic and homogeneous universe is studied. The background geometry in the early phases of the universe is conjectured to be filled with causal bulk viscous cosmological fluid and dark energy. The energy density relations obtained from the assumption of covariant conservation of energymomentum tensor of the background matter in the early universe are used to derive the basic equation for the Hubble parameter $H$. The viscous properties described by ultrarelativistic equations of state and bulk viscosity taken from recent heavyion collisions and lattice QCD calculations have been utilized to give an approximate solution of the field equations. The cosmological constant is conjectured to be related to the energy density of the vacuum. In this treatment, there is a clear evidence for singularity at vanishing cosmic time $t$ indicating the dominant contribution from the dark energy. The time evolution of $H$ seems to last for much longer time than the ideal case, where both cosmological constant and viscosity coefficient are entirely vanishing.
 Publication:

Annalen der Physik
 Pub Date:
 May 2011
 DOI:
 10.1002/andp.201100038
 arXiv:
 arXiv:1102.2626
 Bibcode:
 2011AnP...523..423T
 Keywords:

 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology
 EPrint:
 9 pages, 4 eps figures, 5 eps graphs, revtex4style. arXiv admin note: text overlap with arXiv:grqc/0110119 and arXiv:1001.2814