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 energy-momentum 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 ultra-relativistic equations of state and bulk viscosity taken from recent heavy-ion 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.

9 pages, 4 eps figures, 5 eps graphs, revtex4-style. arXiv admin note: text overlap with arXiv:gr-qc/0110119 and arXiv:1001.2814

References in corpus (8)

• Dynamics of dark energy
• Relativistic viscous hydrodynamics, conformal invariance, and holography
• The QCD Equation of State with almost Physical Quark Masses
• Equation of state and QCD transition at finite temperature
• A calculation of the bulk viscosity in SU(3) gluodynamics
• Bulk viscosity of QCD matter near the critical temperature
• Early Time Evolution of High Energy Heavy Ion Collisions
• Cosmological applications of a geometrical interpretation of "c"

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