ar X iv : n uc l - th / 9 30 70 03 v 1 2 J ul 1 99 3 THE SINGLE - PARTICLE SPECTRAL FUNCTION OF 16

The influence of short-range correlations on the p-wave single-particle spectral function in 16O is studied as a function of energy. This influence, which is represented by the admixture of high-momentum components, is found to be small in the p-shell quasihole wave functions. It is therefore unlikely that studies of quasihole momentum distributions using the (e, ep) reaction will reveal a significant contribution of high momentum components. Instead, high-momentum components become increasingly more dominant at higher excitation energy. The above observations are consistent with the energy distribution of high-momentum components in nuclear matter. PACS numbers: 21.10.Jx, 24.10Cn, 27.20.+n Typeset using REVTEX 1 The influence of short-range correlations in finite nuclei has been studied theoretically by calculating the momentum distribution in the ground state of a particular nucleus [1–5]. These results clearly show that for momenta above 400 MeV/c short-range and tensor correlations completely dominate the momentum distribution. The momentum distribution for a given lj-combination is given by nlj(k) = 〈Ψ0| a † kljaklj |Ψ0〉 . (1) The total momentum distribution is obtained by summing over all lj combinations multiplying each contribution with the relevant degeneracy factor. It is possible to rewrite Eq. (1) by inserting a complete set of A− 1 particle states with the result nlj(k) = ∑ n |〈Ψn| aklj |Ψ0〉| 2 . (2) In a simple mean-field description this sum is exhausted by the transition from the ground state of the A particle system to the ground state of the A − 1 particle system when the lj combination corresponds to the last occupied single-particle level. In that case Eq. (2) represents nothing but the square of the corresponding single-particle wave function in momentum space. When correlations beyond the mean field are present, this is no longer true, although the ground state to ground state transition might still dominate at least for small momenta. This has been observed in Ref. [6] for the momentum distribution of He. In this work the ground state to ground state transition was calculated for both He and He. For He some sensitivity to short-range correlations was observed in the second maximum. From a comparison to the total momentum distribution of He, which is calculated in Ref. [7], it becomes clear, however, that the ground state to ground state contribution to Eq. (2) contributes only an insignificant fraction of the high momentum components. From Eq. (2) one may thus infer that the high-momentum components must come from the contribution of excited states in the A − 1 system. In other words, one requires knowledge of the complete energy dependence of the nucleon hole spectral function