Locating the QCD critical point with neutron-star observations

Abstract

We present a probabilistic model for the QCD critical endpoint (CEP) and the equation of state (EOS) at $\beta$-equilibrium, constrained by neutron-star observations. Using a hybrid framework that combines the holographic V-QCD model with an effective van der Waals description of nuclear matter, we generate a large ensemble of EOSs incorporating nuclear theory uncertainties. Constraining this ensemble with neutron-star mass-radius data and tidal deformability measurements from gravitational waves, we identify a strong first-order deconfinement transition at zero temperature, with a transition strength of $\Delta n_{\mathrm{PT}}/n_0=3.75_{-0.53}^{+0.70}$ and onset density $n_{\mathrm{PT}}/n_0=4.9_{-1.17}^{+1.33}$. The resulting posterior yields $95\%$ credible intervals for the CEP location: ${\mu }_{\mathrm{crit}}=626_{-179}^{+90}\mathrm{MeV}$, $T_{\mathrm{crit}}=119_{-6}^{+14}\mathrm{MeV}$.

Comments: 9 pages, 5 figures