Low-density homogeneous symmetric nuclear matter: Disclosing dinucleons in coexisting phases

Abstract

The effect of in-medium dinucleon bound states on self-consistent single-particle fields in Brueckner, Bethe and Goldstone theory is investigated in symmetric nuclear matter at zero temperature. To this end, dinucleon bound state occurences in the 1 S0 and 3 SD1 channels are explicitly accounted for -within the continuous choice for the auxiliary fields-while imposing self-consistency in Brueckner-Hartree-Fock approximation calculations. Searches are carried out at Fermi momenta in the range 0 < kF = 1.75 fm-1, using the Argonne v18 bare nucleon-nucleon potential without resorting to the effective-mass approximation. As a result, two distinct solutions meeting the self-consistency requirement are found with overlapping domains in the interval 0.130 fm-1 = kF = 0.285 fm-1, corresponding to mass densities between 10 11.4 and 10 12.4 g cm-3. Effective masses as high as three times the nucleon mass are found in the coexistence domain. The emergence of superfluidity in relationship with BCS pairing gap solutions is discussed.