Effective degrees of freedom during the radiation era

This is a physics paper that grew out of my collaboration with Matts Roos in his publication of the 3rd edition of his text Introduction to Cosmology. This paper updates the curves of the effective degrees of freedom for the energy density g*(T) and for the entropy density g*S(T) during the era of radiation domination in the Universe. We find that a plain count of effective degrees of freedom sets an upper limit to the temperature of the quark-hadron transition at TQCD< 235 MeV for the energy density and TQCD< 245 MeV for the entropy density.

Thomas S. Coleman and Matts Roos, Physical Review D 68 027702 (2003), e-print at http://arxiv.org/abs/astro-ph/0304281

About Thomas Coleman

Thomas S. Coleman is Senior Advisor at the Becker Friedman Institute for Research in Economics and Adjunct Professor of Finance at the Booth School of Business at the University of Chicago. Prior to returning to academia, Mr. Coleman worked in the finance industry for more than twenty years with considerable experience in trading, risk management, and quantitative modeling. Mr. Coleman earned a PhD in economics from the University of Chicago and a BA in physics from Harvard College.
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