Cosmological Implications of QGP Bulk Viscosity

TL;DR

This paper explores how the sharp increase in QGP bulk viscosity near the QCD critical point can cause rapid cosmic inflation and cavitation, impacting early universe evolution.

Contribution

It demonstrates that QGP bulk viscosity can induce inflation and cavitation in the early universe, independent of the QCD phase transition order.

Findings

Universe expands by a factor of 10 to 80 within 10^{-8} seconds.

Bulk viscosity causes effective negative pressure leading to inflation.

Cavitation bubbles form within QGP around 1.5 times the critical temperature.

Abstract

Recent studies of the hot QCD matter indicate that the bulk viscosity ($\zeta$) of quark-gluon plasma (QGP) rises sharply near the critical point of the QCD phase transition. In this work, we show that such a sharp rise of the bulk viscosity will lead to an effective negative pressure near the critical temperature, $T_{c}$ which in turn drives the Universe to inflate. This inflation has a natural graceful exist when the viscous effect evanesce. We estimate that, depending upon the peak value of $\zeta$, universe expands by a factor of $10$ to $80$ times in a very short span ($\Delta t\sim 10^{-8}$ seconds). Another important outcome of the bulk viscosity dominated dynamics is the cavitation of QGP around $T \sim 1.5T_{c}$. This would lead to the phenomenon of formation of cavitation bubbles within the QGP phase. The above scenario is independent of the order of QCD phase transition. We delineate some of the important cosmological consequences of the inflation and the cavitation.