On Effective Degrees of Freedom in the Early Universe
By Lars Husdal. 2016
240 citations recorded by the source corpus.
We explore the effective degrees of freedom in the early Universe, from before the electroweak scale at a few femtoseconds after the Big Bang until the last positrons disappeared a few minutes later. We look at the established concepts of effective degrees of freedom for energy density, pressure, and entropy density, and introduce effective degrees of freedom for number density as well. We discuss what happens with particle species as their temperature cools down from relativistic to semi- and non-relativistic temperatures, and then annihilates completely. This will affect the pressure and the entropy per particle. We also look at the transition from a quark-gluon plasma to a hadron gas. Using a list a known hadrons, we use a “cross-over” temperature of 214 MeV, where the effective degrees of freedom for a quark-gluon plasma equals that of a hadron gas.
Subfields: Atmospheric Science, Nuclear and High Energy Physics, Statistical and Nonlinear Physics
View Paper: https://www.semanticscholar.org/paper/024ae4548d2c6ab8046b5c70f0958e00dede178f
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In Atmospheric Science
In Nuclear and High Energy Physics
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Citations in the corpus
- From NANOGrav to LIGO with metastable cosmic strings (2020, methodology): “For the evolution of the degrees of freedom we use the results of [31] for the SM degrees of freedom and moreover include supersymmetric degrees of freedom at a threshold value of 2 TeV.”
- Gravitational wave constraints on the primordial black hole dominated early universe (2020, background): “[67, 68] for a review on their dependence with the temperature).”