C. Ciofi degli Atti

Analysis of the proton momentum distribution in 3He

Abstract The proton momentum distribution in 3 He, calculated variationally from the Reid soft core interaction, is compared with momentum distributions for other nuclei and for nuclear matter.

Realistic many-body wave functions and nucleon momentum distributions in finite nuclei

Abstract The nucleon momentum distributions n(k) in 12C, 16O and 40Ca have been calculated within a many-body approach and using a realistic nucleon-nucleon interaction. Our results satisfactorily agree with those obtained within the Brueckner-Bethe-Goldstone theory and, at the same time, yield a much larger content of high momentum components with respect to the results obtained within the Hartree-Fock approach or within methods taking into account the effects of correlations phenomenologically.

Nucleon-nucleon correlations and final state interaction in inclusive quasi-elastic electron scattering off nuclei at x > 1

Abstract Inclusive quasi-elastic electron scattering off nuclei is investigated at high momentum transfer ( Q 2 > 1 (GeV/ c ) 2 ) and x > 1 adopting a consistent treatment of nucleon-nucleon correlations in initial and final states. It is shown that in case of light as well as complex nuclei the inclusive cross section at 1.3 x x > 2 it is governed by the rescattering of the outgoing off-mass-shell nucleon in the complex optical potential generated by the ground state of the residual (A - 1)-nucleon system.

On the theoretical description of y-scaling effects in inclusive electron scattering by the 3He nucleus

Abstract Experimental and theoretical scaling functions for the three-body system are compared within PWIA. It is shown that such a comparison can provide useful and non trivial information about the removal energy structure of the spectral function.

Calculations of nuclear matter with state-dependent correlations and a semirealistic nucleon-nucleon potential

Abstract The energy of nuclear matter in correspondence to a semirealistic nucleon-nucleon interaction was calculated within the framework of the Jastrow variational approach with state dependent correlation functions. Many-body cluster contributions were evaluated by means of generalized Fermion-Hyper-Netted-Chain integral equations.

Nucleon momentum distributions, their spin-isospin dependence, and short-range correlations

The nucleon momentum distribution nA(k) for A=2, 3, 4, 16, and 40 nuclei is systematically analyzed in terms of wave functions resulting from advanced solutions of the nonrelativistic Schrodinger equation, obtained within different many-body approaches based upon different realistic bare nucleon-nucleon (NN) interactions featuring similar short-range repulsion and tensor interactions. Particular attention is paid to the separation of the momentum distributions into the mean-field and short-range correlation (SRC) contributions. It is shown that although at high values of the momentum k different approaches lead to some quantitative differences, these do not hinder the general conclusion that the high-momentum behavior (k≳1.5–2 fm−1) of all nuclei considered are very similar, exhibiting the well-known scaling behavior with the mass number A, independently of the used many-body approach and the details of the bare NN interaction. To analyze and understand the frequently addressed question concerning the relationships between the nucleus, nA(k), and the deuteron, nD(k), momentum distributions, the spin (S)-isospin (T) structure of few-nucleon systems and complex nuclei is analyzed in terms of realistic NN interactions and many-body approaches. To this end, the number of NN pairs in a given (ST) state, viz., (ST)=(10), (00), (01), and (11), and the contribution of these states to the nucleon momentum distributions are calculated. It is shown that, apart from the (00) state, which has very small effects, all other spin-isospin states contribute to the momentum distribution in a wide range of momenta. It is shown that for all nuclei considered the momentum distributions in the states T=0 and T=1 exhibit at k≳1.5–2 fm−1 very similar behaviors, which represents strong evidence of the A-independent character of SRCs. The ratio nA(k)/nD(k) is analyzed in detail, stressing that in the SRC region it always increases with the momentum and the origin of such an increase is discussed and elucidated. The relationships between the one- and two-body momentum distributions, considered in a previous paper, are discussed and clarified, pointing out the relevant role played by the center-of-mass motion of a correlated pair in the (10) state. Eventually, the values of the the probability of high-momentum components in nuclei and the per nucleon probability a2 of deuteronlike configurations in nuclei are calculated, and the relationship of the present approach with the many-body methods based upon low-momentum effective interactions is briefly discussed.

On the extraction of the neutron spin structure functions and the Gerasimov-Drell-Hearn integral from the process He→3(e→,e′) in the resonance region

Abstract Nuclear effects in polarized inelastic electron scattering off polarized 3He are discussed; in the kinematics of future experiments at TJNAF, Fermi motion effects are found to be much larger than in deep inelastic scattering. It is shown that improperly describing nuclear dynamics would lead to the extraction of unreliable neutron spin structure functions. On the other hand side, a simple and workable equation relating the Gerasimov-Drell-Hearn Integral for the neutron to the corresponding quantity for 3He is proposed.

Variational calculation of nuclear matter

Abstract The energy of nuclear matter has been calculated variationally with an approach based on FHNC equations which include central spin, isospin and tensor correlations. Various types of two-body interactions, namely the 5200, the model Reid V6, the Hamada-Johnston and the full Reid soft-core interactions have been considered. The results of the calculations have been compared with the results of other types of variational methods as well as with the results of Brueckner-Bethe-Goldstone approaches.

Subsidiary conditions and variational calculations of nuclear and neutron matters

Abstract The energy of nuclear and neutron matter is calculated within the framework of the variational approach including the contribution from three-body clusters. Two types of constrains for the two-body correlation function and realistic S-wave forces are used. It is shown that the energy strongly depends upon the type of constraint and that the variational calculation may lead to much more energy than the lowest order Brueckner theory calculations.

Final-state interaction effects in semi-exclusive DIS off the deuteron

Abstract.The effects of the final-state interaction (FSI) in semi-exclusive deep inelastic scattering of electrons off the deuteron are analyzed paying particular attention to two extreme kinematical regions: i) the one where FSI effects are minimized, so that the quark distribution of bound nucleons could be investigated, and ii) the one where the re-interaction of the produced hadrons with the spectator nucleon is maximized, which would allow one to study the mechanism of hadronization of highly virtual quarks. It is demonstrated that when the recoiling spectator nucleon is detected in the backward hemisphere with low momentum, the effects from the FSI are negligible, whereas at large transverse momenta of the spectator, FSI effects are rather large. Numerical estimates show that the FSI corrections are sensitive to the theoretical models of the hadronization mechanism.