Elimination of 0+ spurious states in the quasiparticle time blocking approximation
Abstract
The quasiparticle time blocking approximation (QTBA) is considered as a model for the description of excitations in open-shell nuclei. The QTBA is an extension of the quasiparticle random phase approximation that includes quasiparticle-phonon coupling. In the present version of the QTBA, the pairing correlations are included within the framework of the BCS approximation. Thus, in this model, the 0+ spurious states appear, which are caused by the breaking of the symmetry related to the particle-number conservation. In this work, the method is described which solves the problem of the 0+ spurious states in the QTBA with the help of the projection technique. The method is illustrated by calculations of 0+ excitations in 120Sn nucleus.
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