Mapping out the thermodynamic stability of a QCD equation of state with a critical point using active learning

Understand

The Beam Energy Scan Theory (BEST) collaboration's equation of state (EoS) incorporates a 3D Ising model critical point into the Quantum Chromodynamics (QCD) equation of state from lattice simulations.

• However, it contains 4 free parameters related to the size and location of the critical region in the QCD phase diagram.
• Certain combinations of the free parameters lead to acausal or unstable realizations of the EoS that should not be considered.
• In this work, we use an active learning framework to rule out pathological EoS efficiently.