PAIRING AS A COLLECTIVE MODE

Abstract

The collective pairing hamiltonian is obtained in the framework of the generator coordinate method using the Gaussian overlap approximation. A slightly modified BCS wave function is used as a generator function. The pairing gap parameter Δ and the gauge transformation angle ϕ are chosen as generator coordinates. This model gives not only an approximate particle-number projection but also the form of the ground state collective wave function in the (Δ, ϕ) plane. It was found that the most probable Δ does not corresponds to the minimum (Δ eq ) of the energy function E BCS (Δ) but it is systematically shifted towards smaller values than Δ eq . This effect is due to the strong dependence of the mass parameters on the pairing gap. The influence of the dynamics in the pairing degrees of freedom on the fission life-times as well as the quadrupole collective excitations is examined.