Particle-number fluctuation of pairing correlations for Dy isotopes

Within the relativistic mean field （RMF） theory, the ground state properties of dysprosium isotopes are studied using the shell-model-like approach （SLAP）, in which pairing correlations are treated with particle- number conservation, and the Pauli blocking effects are taken into account exactly. For comparison, calculations of the Bardeen Cooper Schrieffer （BCS） model with the RMF are also performed. It is found that the RMF＋SLAP calculation results, as well as the RMF＋BCS ones, reproduce the experimental binding energies and one- and twoneutron separation energies quite well. However, the RMF＋BCS calculations give larger pairing energies than those obtained by the RMF＋SLAP calculations, in particular for nuclei near the proton and neutron drip lines. This deviation is discussed in terms of the BCS particle-number fluctuation, which leads to the sizable deviation of pairing energies between the RMF＋BCS and RMF＋SLAP models, where the fluctuation of the particle number is eliminated automatically.