Effect of the continuum on pairing enhancement in a two-neutron transfer process

The quantification of pairing interaction in a two-neutron transfer through the intermediary continuum

“…The result is similar to the one presented in Ref. [11]. This rise in the cross-sections due to the intermediary continuum can in a way supplement and aid the formation of Borromean halos in stellar plasma.…”

“…In fact, even the configurations where one of the particles is in the ground state, while the other is in any of the excited states of the continuum (|1, j configurations, see Ref. [11] for details), the contributions are small, but perhaps still measureable. The continuum states offer little to no contribuion in these cases.…”

“…Such a study, trying to quantify the role of the continuum, was done in Ref. [11], where we studied the role of the intermediate continuum on pairing enhancement, fixing the ground state of the final nucleus 6 He at the usual 0.975 MeV below zero. The pairing was introduced as a perturbation to the system and the entire premise was compared with a hypothetical case where the intermediate 5 He nucleus was considered to be bound.…”

“…It was found that in the naturally occuring unbound case, the continuum provided significant enhancement to the two-neutron transfer cross-section. Since continuum wave functions are difficult to work with, the continuum was discretised using a transformed harmonic oscillator (THO) basis [2,11] and the resonance state for the continuum case (the third state in our basis) was fixed at 0.69 MeV.…”

“…However, unlike the study in Ref. [11], where we varied the pairing strength ∆ (described using a contact delta interaction of the form −gδ( r 1 − r 2 ), g being the coupling constant. The value of g is what modifies the perturbation to the uncompromised Hamiltonian.…”