Lattice QCD for Cosmology

TL;DR

This paper provides detailed lattice QCD calculations of the universe's equation of state across a wide temperature range, including effects of electroweak theory, and explores implications for dark matter axion properties.

Contribution

It extends lattice QCD calculations to 2+1+1+1 flavors and incorporates electroweak effects to model cosmological evolution and dark matter axion constraints.

Findings

Equation of state for 2+1+1+1 flavor QCD across broad temperature range

Calculated topological susceptibility up to a few GeV temperature

Provided relations between axion mass, initial angle, and universe evolution

Abstract

We present a full result for the equation of state (EoS) in 2+1+1 (up/down, strange and charm quarks are present) flavour lattice QCD. We extend this analysis and give the equation of state in 2+1+1+1 flavour QCD. In order to describe the evolution of the universe from temperatures several hundreds of GeV to several tens of MeV we also include the known effects of the electroweak theory and give the effective degree of freedoms. As another application of lattice QCD we calculate the topological susceptibility (chi) up to the few GeV temperature region. These two results, EoS and chi, can be used to predict the dark matter axion's mass in the post-inflation scenario and/or give the relationship between the axion's mass and the universal axionic angle, which acts as a initial condition of our universe.