The effects of the final state interaction on the production of slow protons in semi-inclusive deep-inelastic lepton scattering off nuclei is considered within the spectator mechanism and a realistic approach in which the rescattering in the medium of both the recoiling proton and the hadronizing nucleon debris are taken into account.
The effects of the final state interaction in slow proton production in semi inclusive deep inelastic scattering processes off nuclei, A(e,ep)X, are investigated in details within the spectator and target fragmentation mechanisms; in the former mechanism, the hard interaction on a nucleon of a correlated pair leads, by recoil, to the emission of the partner nucleon, whereas in the latter mechanism proton is produced when the diquark, which is formed right after the visrtual photon-quark interaction, captures a quark from the vacuum. Unlike previous papers on the subject, particular attention is paid on the effects of the final state interaction of the hadronizing quark with the nuclear medium within an approach based upon an effective time-dependent cross section which combines the soft and hard parts of hadronization dynamics in terms of the string model and perturbative QCD, respectively. It is shown that the final state interaction of the hadronizing quark with the medium plays a relevant role both in deuteron and complex nuclei; nonetheless, kinematical regions where final state interaction effects are minimized can experimentally be selected, which would allow one to investigate the structure functions of nucleons embedded in the nuclear medium; likewise, regions where the interaction of the struck hadronizing quark with the nuclear medium is maximized can be found, which would make it possible to study non perturbative hadronization mechanisms.
The effects of the final state interaction (FSI) in semi inclusive deep inelastic electron scattering processes $A(e,ep)X$ off nuclei are investigated in details. Proton production is described within the spectator and the target fragmentation mechanisms whose relevance to the experimental study of the deep inelastic structure functions of bound nucleons and the non perturbative hadronization process is analyzed. Particular attention is paid to the deuteron target within kinematical conditions corresponding to the available and forthcoming experimental data at Jlab. We argue that there are kinematical regions where FSI effects are minimized, allowing for a reliable investigation of the DIS structure functions, and regions where the interaction of the quark-gluon debris with nucleons is maximized, which makes it possible to study hadronization mechanisms. Nuclear structure has been described by means of realistic wave functions and spectral functions and the final state interaction has been treated within an eikonal approximation approach which takes into account the rescattering of the quark-gluon debris with the residual nucleus and, in the case of complex nuclei, within an optical potential approach to account for the FSI of the struck proton.
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<2 is dominated by the absorption of the virtual photon on a pair of correlated nucleons and by their elastic rescattering in the continuum, whereas at 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.
We discuss a new approach to final state interactions, that keeps explicitly into account the virtuality of the ejected nucleon in quasi-elastic $A(e,ep)X$ scattering at very large $Q^2$, and we present some recent results, at moderately large $Q^2$ values, for the nuclear transparency in $^4He$, $^{16}O$ and $^{40}Ca$ and for the momentum distributions of $^4He$.
A calculation of nuclear effects in the extraction of neutron single spin asymmetries in semi-inclusive deep inelastic scattering off 3He is described. In the kinematics of forth-coming experiments at JLab, it is found that the nuclear effects arising within an Impulse Approximation approach are under control.
M. Alvioli
,C. Ciofi degli Atti
,V. Palli
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(2006)
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"Slow proton production in semi-inclusive DIS off nuclei: the role of final state interaction"
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Claudio Ciofi degli Atti
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