Paper detail

Competition between fermions and bosons in nuclear matter at low densities and finite temperatures

We derive the free energy for fermions and bosons from fragmentation data. Inspired by the symmetry and pairing energy of the Weizsacker mass formula we obtain the free energy of fermions (nucleons) and bosons (alphas and deuterons) using Landau's free energy approach. We confirm previously obtained results for fermions and show that the free energy for alpha particles is negative and very close to the free energy for ideal Bose gases. Deuterons behave more similarly to fermions (positive free energy) rather than bosons. This is due to their low binding energy, which makes them very 'fragile', i.e., easily formed and destroyed. We show that the α-particle fraction is dominant at all temperatures and densities explored in this work. This is consistent with their negative free energy, which favors clusterization of nuclear matter into α-particles at subsaturation densities and finite temperatures. The role of finite open systems and Coulomb repulsion is addressed.