Baryon-number fluctuations in a quark-hadron phase transition

Abstract

Isothermal baryon-number fluctuations arising from a first-order quark-hadron phase transition in the early Universe are obtained by including the quark-gluon interactions up to the order ${\mathit{g}}_{\mathit{s}}^3$ in the perturbative QCD coupling constant in the quark-gluon plasma (QGP) phase and the finite-size volume corrections for the hadrons in the hadron-resonance gas (HRG) and their effects on the primordial nucleosynthesis (PNS) are analyzed. The ratio of the baryon-number densities in the QGP and HRG phases at the critical temperature ${\mathit{T}}_{\mathit{c}}$ is larger than one in the range 150 MeV${\mathit{T}}_{\mathit{c}}$${\mathit{T}}_{\mathit{c}}$ is outside this range, thus affecting primordial nucleosynthesis significantly.