QCD relics in the present-day Universe?

A possibility is suggested for the formation in the Universe of domains occupied by coherent-like states of strongly correlated quark-antiquark pairs. Only domains of the radius larger than 5 fm had a chance to survive over the entire history of the Universe, while the requirement of stability against the gravitational collapse restricts the maximum domain's radius to 14 km. Within the Generalised Nambu-Jona-Lasinio model, an exponential suppression with the domain's volume is found for the overlap between the macroscopic ground-state wavefunction of the quark-antiquark pairs and the QCD vacuum. This finding supports, at the microscopic level, the above arguments in favour of the stability of the domains.