Within General Relativity there is a maximum latent heat for a first order phase transition that a neutron star can support, the Seidov limit. If neutron-star matter exceeds it, the transition to the presumed exotic phase will not be complete before the star undergoes gravitational collapse.
However, this limit should generally be different in theories of modified gravity, that are to be tested in neutron star interiors (the place where the stress-energy tensor is largest). It is then interesting to ascertain what is the strongest possible phase transition, as quantified by its latent heat, that hadron physics can still allow on its own.
For this we apply the nEoS sets developed by us in collaboration with Mark Alford and Andreas Windisch https://doi.org/10.1088/1361-6471/ab2567 and that rely on extant ChPT and pQCD calculations (in the respective low- and high-density limits) and first principles alone, without reference to any astrophysical observables, making them free of assumption about the theory of gravity at the star.
We obtain a bound on the maximum latent heat as function of the density (at zero temperature) at which the phase transition triggers, independently of GR. It is currently less tight than the Seidov limit and can serve as a benchmark for future progress on the equation of state from hadron physics alone.