Can the effects of tetraneutron correlations be observed in low-density, laboratory-accessible, neutron-rich matter?

Abstract

Multi-nucleon correlations, present in low- density neutron-rich matter may play an important role in astrophysical environments. In the laboratory heavy-ion collisions and ternary fission are capable of producing neutron enriched matter having thermodynamic conditions of low densities and moderate temperatures similar to those encountered in neutron star crusts, supernovae and binary mergers. In this work, we study the effect of including a resonant state of four neutrons in the low-density warm nuclear equation of state, using a relativistic mean-field formalism, where in-medium effects are considered. For that purpose, the abundances of isotopes \(Z\le 6\) immersed in a gas of protons and neutrons, are calculated with and without the presence of this resonant tetra-neutron state. To provide a baseline test of this approach, the yields of isotopes calculated with and without the tetra-neutron included are then compared with experimentally observed ternary fission yields. While the results indicate that the tetra-neutron has little effect on yields of other clusters under the existing ternary fission conditions, a possibly observable effect on yields of clusters emitted from the neck region in mid-peripheral heavy ion collisions is suggested.