Quasiparticle Cosmology

TL;DR

This paper explores a quasiparticle thermodynamic model of the universe where thermal mass effects can produce negative pressure, potentially mimicking dark energy, validated through scalar field theory and QCD axion applications.

Contribution

It introduces a novel thermodynamic framework linking thermal mass variations to dark energy-like effects in cosmology.

Findings

Thermal mass variations can induce negative pressure similar to dark energy.

The framework is validated using scalar field theory results.

Application demonstrated on QCD axion model.

Abstract

We consider thermodynamics of the Universe within a quasiparticle approach where the collective dynamics of a system is governed by the thermal mass of the constituents. The spacetime dependence of this thermal mass leads to a negative contribution to the pressure and a positive contribution to the energy density, similar to the effect due to dark energy. We propose a mechanism based on thermodynamic arguments to quantify this contribution from the thermal vacuum of the system. For a sufficiently large spacetime variation of the thermal mass, the effective pressure can become negative and could mimic a dark energy equation of state. We validate our framework using results from renormalizable interacting scalar field theory and demonstrate an application on QCD axion.