Model calculations with pairing forces

B. Atalay, D.M. Brink, A. Mann

Raoul Rashidovich Nigmatullin

B. F. Bayman

Yang Yi, Gong-ou Xu

Microscopic investigation of collective models is illustrated with the study of the multilevel pairing force model. The coherent-state description of pairing excitations through the variation of the pairing field and the classification of generators into collective and noncollective modes are discussed. Numerical calculations are performed for collective pairing rotations and vibrations built on the ground state. The coupling to the noncollective state is studied. Exact results from the Richardson method are given for comparison.

J. Eichler, M. Yamamura

G. W. Ford, Robert F. O’Connell

Here the problem considered is that of a pair of oscillators coupled to a common heat bath. Many, if not most, discussions of a single operator coupled to a bath have used the independent oscillator model of the bath. However, that model has no notion of separation, so the question of phenomena when the oscillators are near one another compared with when they are widely separated cannot be addressed. Here the Lamb model of an oscillator attached to a stretched string is generalized to illustrate some of these questions. The coupled Langevin equations for a pair of oscillators attached to the string at different points are derived and their limits for large and small separations obtained. Finally, as an illustration of a different phenomenon, the fluctuation force between a pair of masses attached to the string is calculated, with closed-form expressions for the force at small and large separations.