Semi-classical description of a system with proton–neutron interaction

New results for 2νββ decay with large particle–particle two-body proton–neutron interaction

“…Since the coherent state for SU (2) and for the Weyl group are formally identical with the difference that in the first case the operators A † , A satisfy exact commutation relations, while in the later case they are considered as quasibosons, we complete our study with a fourth wave function which is similar to the SU(1,1) coherent state but the operators involved satisfy exact commutation relations. Concluding, the following trial functions have been alternatively considered for the variational state [26,27]:…”

“…For a better presentation the final results will be considered, as in ref. [26,29], as function of the re-scaled strengths of particle-hole and particle-particle interactions:…”

“…As we showed in ref. [26] the HP boson expansion is defined in that interval of k' where the standard pnQRPA does not work.…”

“…6.20 and 6.28 of ref. [26]). Assuming for the operators A † involved in (5.1,5.2) quasiboson commutation relations one obtains the following expressions for the norms.…”

“…The new methods tried either to keep the pnQRPA boson picture but include higher correlations through boson expansion [14][15][16][17][18][19] techniques or via self-consistent procedures [20], or to re-normalize the pnQRPA phonon [21][22][23][24]. These methods improved the description of the data [25] although they have also drawbacks and lack sometimes of consistency [24,26,28].…”