The map of dense nuclear matter resembles a road map: lines of phase transitions cross at critical points, like highways at intersections. Until now, only two intersections were known on such a map: the nuclear liquid-gas and deconfinement, where hadrons dissolve into quarks. Now, the authors have added a third intersection, leading to a strangeness-dominated phase.

To draw such a map, the scientists used the chiral mean-field model CMF++. It accounts for the symmetry of strong interactions and includes the full set of baryons and quarks. The equation of state is calculated in a four-dimensional space: temperature, baryon, strange, and electric chemical potentials. Stable and unstable solutions are determined via the Hessian matrix, and critical points are identified from peaks in baryon susceptibility.

At zero temperature, three phases are found: a light hadronic phase (mostly nucleons), a quark phase, and a strange phase. Upon heating, each first-order transition ends at a critical point. For the strange transition, the critical temperature $T_c$ ≈ 40 MeV, which corresponds to roughly 460 billion kelvin—tens of thousands of times hotter than the center of the Sun. At low temperatures, the deconfinement line bends toward lower baryon chemical potentials, opposite to standard behavior.

Previously, it was unknown whether the hyperonic phase could coexist with the nuclear liquid-gas and deconfinement transitions in a single model. Now it is shown that, under certain parameters, three separate critical points emerge. This is the first demonstration of three intersections on a single map of dense matter.

The result is important for understanding the composition of neutron star interiors and the dynamics of their mergers. Future heavy-ion collision experiments could test whether the strange phase appears under real conditions. If so, the map of dense matter will become even more detailed, and the intersections more predictable.