An upper limit on mass density of quark nuggets from the microlensing event statistics

Abstract

We calculate the spectrum of separations between nucleation sites hadron bubbles formed during the first-order cosmic QCD phase transition considered within the Lee-Wick model, an effective QCD model. On the basis of the separation spectrum, we construct a naive model mass spectrum of quark nuggets. Using this mass spectrum and the microlensing event statistics of the MACHO group, we place an upper limit on the mass density of quark nuggets in the galactic halo.