VISCOUS PROPERTIES OF QUARK-GLUON PLASMA AND THEIR COSMIC IMPACTS

Abstract

We condensate on the application and impacts of viscous Quark-gluon-plasma into the early Uni- verse cosmology, Considering Friedmann-Lemaitre-Robertson-Walker Universe which the evolution is aflat, isotropic and homogeneous. First, take a simple system (closed system) which consists of one particle and one photon which particle represent matter and photon represent radiation. Other components such as dark matter and dark energy (cosmological constant) are not taken into con- sideration. By introducing a toy model based on a thermodynamical approach in order to propose a framework forfinite bulk viscosity for the cosmic background (Friedmann-model). By applying thermodynamics in order to drive expressions for various cosmological quantities, such as the scale factora(t) and the Hubble parameterH(t), energy densityρand bulk viscosityζ. Throughout this work, assume natural units for all physical quantities. Then, take open system and determine the equation of state and related with temperature and time dependence, properties of QGP, evo- lution of the cosmic parameters, the bulk viscose pressure related with Hubble parameter and time plank. From LQCD data,finding proposal equations represented in relation of energy densityρ, pressurep, with temperatureTand related by equation of state (EoS). Entropy densitys, speed of sound squaredC s2, bulk viscosityζ, shear viscosityηand ratios of coefficient of viscosity related to temperatureT. Proposal equation between temperatureTand timet, wherefore determine proposal equation of Hubble parameterH(t) and the scale factora(t) related with temperatureT. Finally, the cosmological parameter of second order of causal Eckart frame is determined i.e. (first derivative of the Hubble parameterH(t), energy densityρand bulk viscosityζand shear viscosity ηand bulk viscous pressureΠ.