Quark-Gluon Plasma as the Possible Source of Cosmological Dark Radiation

Abstract

The effective number of neutrinos, $N_{\text{eff}}$, obtained from CMB fluctuations accounts for all effectively massless degrees of freedom present in the Universe, including but not limited to the three known neutrinos. Using a lattice-QCD derived QGP equation of state, we constrain the observed range of $N_{\text{eff}}$ in terms of the the freeze-out of unknown degrees of freedom near to quark-gluon hadronization. We explore limits on the coupling of these particles, applying methods of kinetic theory. We present bounds on the coupling of such particles and discuss the implications of a connection between $N_{\text{eff}}$ and the QGP transformation for laboratory studies of QGP.

5 pages, 2 figures

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• The equation of state in (2+1)-flavor QCD
• Full result for the QCD equation of state with 2+1 flavors
• Equation of state and QCD transition at finite temperature
• Relic Neutrino Freeze-out: Dependence on Natural Constants
• Susceptibility of the QCD vacuum to CP-odd electromagnetic background fields
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Cited by in corpus (9)

• Melting Hadrons, Boiling Quarks
• Relic Neutrino Freeze-out: Dependence on Natural Constants
• Cosmological Implications of Light Sterile Neutrinos produced after the QCD Phase Transition
• A short survey of matter-antimatter evolution in the primordial universe
• Cosmological Strangeness Abundance
• Reactions Governing Strangeness Abundance in Primordial Universe
• Quarks to Cosmos: Particles and Plasma in Cosmological evolution
• The hot Hagedorn Universe
• Lepton Number and Expansion of the Universe