Probing QCD critical point and induced gravitational wave by black hole physics

Abstract

Locating the critical endpoint of QCD and the region of a first-order phase transition at finite baryon chemical potential is an active research area for QCD matter. We provide a gravitational dual description of QCD matter at finite baryon chemical potential ${\ensuremath{\mu}}_{B}$ and finite temperature using the nonperturbative approach from gauge/gravity duality. After fixing all model parameters using state-of-the-art lattice QCD data at zero chemical potential, the predicted equations of state and QCD trace anomaly relation are in quantitative agreement with the latest lattice results. We then give the exact location of the critical endpoint as well as the first-order transition line, which is within the coverage of many upcoming experimental measurements. Moreover, using the data from our model at finite ${\ensuremath{\mu}}_{B}$, we calculate the spectrum of the stochastic gravitational wave background associated with the first-order QCD transition in the early Universe, which could be observable via pulsar timing in the future.