Spectroscopic factors for nucleon knock-out fromO16at small missing energy

Abstract

Spectroscopic factors for one-nucleon knockout from 16 O are calculated for states with low excitation energy in 15 N with the Bonn-C potential. A method is proposed to deal with both short-and long-range correlations consistently. For this purpose a Green's function formalism is used and the self-energy in the Dyson equation is approximated as the sum of an energy-dependent Hartree-Fock ͑HF͒ term and dispersion and correlation terms of higher order in the G-matrix interaction. This G matrix is obtained by solving the Bethe-Goldstone equation with a Pauli operator which excludes just the model space treated in the subsequent calculation of the self-energy. The energy dependence of the HF energies induces an additional reduction of the spectroscopic factors for quasiparticle states close to the Fermi level by about 10%. Experimental data may signal the need of some further improvement in the treatment of intermediate-and long-range correlations. ͓S0556-2813͑96͒04105-2͔

Self-consistent Green's function method for nuclei and nuclear matter

“…For an IPM ansatz, the TDA calculation is equivalent to the one of Ref. [195] and yields the same results for the spectroscopic factors of the main particle and hole shells close to the Fermi energy. These correspond to 0.775 for p 1/2 and 0.766 for p 3/2 as reported in Tab.…”

“…The inclusion of the coupling to 2p1h and 2h1p states at low energy has been considered in Refs. [194,195] without leading to an explanation of this discrepancy. In particular, in Ref.…”

“…In Ref. [195], it was found that this procedure properly accounts for the depletion of spectroscopic factors that is induced by SRC, at least for the normally occupied shells in the IPM.…”

“…In particular, in Ref. [195] a successful attempt to combine the Figure 36: Spectroscopic factors from the (e,e ′ p) reaction on 208 Pb for different valence hole orbits. The spectroscopic factor for the main fragment of the 3s 1/2 orbit must be changed to 0.65 from the values in the figure to reflect the analysis given in Ref.…”

“…The calculations of Refs. [194,195] take into account the interaction between the hole and particles propagating in the system at the TDA level and therefore cannot go beyond the 2h1p level. The calculation of Ref.…”