The Cosmological Heavy Ion Collider: Fast Thermalization after Cosmic Inflation. (arXiv:2001.03633v3 [hep-th] UPDATED)

<a href="http://arxiv.org/find/hep-th/1/au:+McDonough_E/0/1/0/all/0/1">Evan McDonough</a>

Heavy-ion colliders have revealed the process of “fast thermalization”. This

experimental breakthrough has led to new theoretical tools to study the

thermalization process at both weak and strong coupling. We apply this to the

reheating epoch of inflationary cosmology, and the formation of a cosmological

quark gluon plasma (QGP). We compute the thermalization time of the QGP at

reheating, and find it is determined by the energy scale of inflation and the

shear viscosity to entropy ratio $eta/s$; or equivalently, the

tensor-to-scalar ratio and the strong coupling constant at the epoch of

thermalization. Thermalization is achieved near-instantaneously in low-scale

inflation and in strongly coupled systems, and takes of order or less than a

single e-fold of expansion for weakly-coupled systems or after high-scale

inflation. We demonstrate that the predictions of inflation are robust to the

physics of thermalization, and find a stochastic background of gravitational

waves at frequencies accessible by interferometers, albeit with a small

amplitude.

Heavy-ion colliders have revealed the process of “fast thermalization”. This

experimental breakthrough has led to new theoretical tools to study the

thermalization process at both weak and strong coupling. We apply this to the

reheating epoch of inflationary cosmology, and the formation of a cosmological

quark gluon plasma (QGP). We compute the thermalization time of the QGP at

reheating, and find it is determined by the energy scale of inflation and the

shear viscosity to entropy ratio $eta/s$; or equivalently, the

tensor-to-scalar ratio and the strong coupling constant at the epoch of

thermalization. Thermalization is achieved near-instantaneously in low-scale

inflation and in strongly coupled systems, and takes of order or less than a

single e-fold of expansion for weakly-coupled systems or after high-scale

inflation. We demonstrate that the predictions of inflation are robust to the

physics of thermalization, and find a stochastic background of gravitational

waves at frequencies accessible by interferometers, albeit with a small

amplitude.

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