Strange Quark Matter Formation During the QCD Epoch: Implications for Dark Matter within the ΛCDM Framework

The QCD phase transition at temperatures T∼150–200T \sim 150–200T∼150–200 MeV represents a well-defined epoch in the standard thermal history of the Universe. While the ΛCDM model successfully describes large-scale cosmological evolution, the microphysics of strongly interacting matter during this epoch remains an active area of theoretical investigation. This work explores the possibility that stable strange quark matter (SQM), as proposed by Edward Witten, may have formed during the QCD transition. If sufficiently stable, strange quark nuggets (SQNs) could survive to the present epoch and contribute to the dark matter density. We analyze formation conditions, stability criteria, relic abundance estimates, and observational constraints. The framework remains fully compatible with ΛCDM cosmology and does not modify inflationary dynamics or the standard expansion history.