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C. Ciofi degli Atti

Publications and source records attributed to C. Ciofi degli Atti.

At least 37 records · Page 2Linked to original sources
arXiv2007

Interpretation of recent JLab results on quasi elastic (e,e'p) reactions off few-nucleon systems

Recent JLab experimental data on quasi elastic 3He(e,e'p)2H(pn) and 4He(e,e'p)3H processes are interpreted using an approach based upon realistic wave functions and Glauber multiple scattering theory within a generalized eikonal approximation (GEA). The results of a non factorized calculation of the left-right asymmetry A_{TL} of the process 3He(e,e'p)2H, obtained using the full covariant form of the electromagnetic operator, are also presented.

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arXiv2007

On the dependence of the wave function of a bound nucleon on its momentum and the EMC effect

It is widely discussed in the literature that the wave function of the nucleon bound in a nucleus is modified due to the interaction with the surrounding medium. We argue that the modification should strongly depend on the momentum of the nucleon. We study such an effect in the case of the point-like configuration component of the wave function of a nucleon bound in a nucleus A, considering the case of arbitrary final state of the spectator A-1 system. We show that for non relativistic values of the nucleon momentum, the momentum dependence of the nucleon deformation appears to follow from rather general considerations and discuss the implications of our theoretical observation for two different phenomena: i) the search for medium induced modifications of the nucleon radius of a bound nucleon through the measurement of the electromagnetic nucleon form factors via the A(e,e'p)X process, and ii) the A-dependence of the EMC effect; in this latter case we also present a new method of estimating the fraction of the nucleus light-cone momentum carried by the photons and find that in a heavy nuclei protons loose about 2% of their momentum.

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arXiv2007

Final State Interaction Effects in Semi-inclusive Deep Inelastic processes A(e,e'p)X off the deuteron and complex nuclei

The effects of the final state interaction (FSI) in semi inclusive deep inelastic electron scattering processes $A(e,e'p)X$ 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.

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arXiv2007

A non factorized calculation of the process ^3He(e,e'p)^2H at medium energies

The exclusive process ^3He(e,e^\prime p)^2H has been analyzed using realistic few-body wave functions corresponding to the AV18 interaction and treating the final state interaction (FSI) within the Eikonal Approximation to describe the multiple rescattering of the struck nucleon with the nucleons of the spectator two-nucleon system. Calculations have been performed in momentum space so that the nucleon electromagnetic current could be left in the fully covariant form avoiding by this way non relativistic reductions and the factorization approximation. The results of calculations, which are compared with recent JLab experimental data, show that the left-right asymmetry exhibit a clear dependence upon the multiple scattering in the final state and demonstrate the breaking down of the factorization approximation at ϕ=0 i.e. for "negative" and large \geq 300MeV/c values of the missing momentum.

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arXiv2007

Effects of correlations on the total neutron-Nucleus cross section at high energies

The total neutron-Nucleus cross section has been calculated within an approach which takes into account nucleon-nucleon correlations, Glauber multiple scattering and inelastic shadowing corrections. Nuclear targets ranging from 4He to 208Pb and neutron incident momentum ranging from 3 to 300 GeV/c, have been considered. Correlations have been introduced by two different approaches leading to the same results. The commonly used approximation, consisting in treating nuclear effects only by a product of one-body densities, is carefully analyzed and it is shown that the effects of realistic correlations resulting from modern nucleon-nucleon interactions and realistic correlations resulting from realistic nucleon-nucleon interactions and microscopic ground state calculation of nuclear properties cannot be disregarded.

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arXiv2006

Hadron Propagation in Medium: the Exclusive Process A(e,e'p)B in Few-Nucleon Systems

The mechanism of propagation of hadronic states in the medium is a key point for understanding particle-nucleus and nucleus-nucleus scattering at high energies. We have investigated the propagation of a baryon in the exclusive process A(e,e'p)B in few-nucleon systems using realistic nuclear wave functions and Glauber multiple scattering theory both in its original form and within a generalized eikonal approximation. New results for the processes 3He(e,e'p)2H and 4He(e,e'p)3H are compared with data recently obtained at the Thomas Jefferson Laboratory (JLAB).

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arXiv2006

A new realistic many-body approach for the description of high-energy scattering processes off complex nuclei

A linked cluster expansion for the calculation of ground state observables of nuclei with realistic interactions has been developed. Using the V8' potential the ground state energy, density and momentum distribution of complex nuclei have been calculated and found to be in good agreement with the results obtained within the Fermi Hyper Netted Chain, and Variational Monte Carlo approaches. Using the same cluster expansion, with wave function and correlations parameters fixed from the calculation of the ground-state observables, various high energy scattering processes off complex nuclei have been calculated taking final state interaction effects into account by means of the Glauber multiple scattering series.

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arXiv2005

A Realistic Calculation of the Effects of Nucleon-Nucleon Correlations in High-Energy Scattering Processes Off Nuclei

A new linked cluster expansion for the calculation of ground state observables of complex nuclei with realistic interactions has been developed [1-3]; using the V8' potential [4] the ground state energy, density and momentum distribution of complex nuclei have been calculated and found to be in good agreement with the results of [5], obtained within the Fermi Hyper Netted Chain, and Variational Monte Carlo [6] approaches. Using the same cluster expansion, with wave function and correlations Realistic Calculation of the Effects of Nucleon-Nucleon Correlations in High-Energy Scattering Processes Off Nuclei parameters fixed from the calculation of the ground-state observables, the semi-inclusive reaction of type A(e,e'p)X has been calculated taking final state interaction effects into account within a Glauber type calculation as in Ref. [7]; the comparison between the resulting distorted and undistorted momentum distributions provides an estimate of the transparency of the nuclear medium to the propagation of the hit proton. The effect of color transparency has also been considered within the approach of [8,9]; it is shown that at high values of Q^2 finite formation time effects strongly reduce the final state interaction, consistently with the idea of a reduced interaction of the hadron produced inside the nucleus [10]. The total neutron-nucleus cross section at high energies has also been calculated [11] by considering the effects of nucleon-nucleon correlations, which are found to increase the cross section by about 10% in disagreement with the experimental data. The inclusion of inelastic shadowing effects of Refs. [12,13] decreases back the cross section, leading to a good agreement between experimental data and theoretical calculations.

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arXiv2005

On the Interpretation of the Processes 3He(e,e'p)2H and 3He(e,e'p)(pn) at High Missing Momenta

It is shown that the effects of the Final State Interaction (FSI) in the exclusive processes 3He(e,e'p)2H and 3He(e,e'p)(pn), can be successfully treated in terms of a Generalized Eikonal Approximation (GEA), based upon the direct calculation of the Feynman diagrams describing the rescattering of the struck nucleon. As a matter of fact, using realistic three-body wave functions corresponding to the AV18 interaction, the results of our parameter free calculation exhibits a very satisfactory agreement with recent experimental data from Jlab covering the region of missing momentum and energy with p_m < 1.0 GeV/c and E_m < 100 MeV. It is demonstrated that the missing momentum dependence of the experimental cross section of the process 3He(e,e'p)2H is mainly governed at p_m < 0.2 GeV/c by the Plane Wave Impulse Approximation (PWIA), at 0.2 < p_m < 0.6 GeV/c by the single rescattering FSI, and at 0.6 GeV/c < p_m by the double rescattering FSI.

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arXiv2005

Ground-state energies, densities and momentum distributions in closed-shell nuclei calculated within a cluster expansion approach and realistic interactions

A linked cluster expansion suitable for the treatment of ground-state properties of complex nuclei, as well as of various particle-nucleus scattering processes, has been used to calculate the ground-state energy, density and momentum distribution of 16-O and 40-Ca using realistic interactions. First of all, a benchmark calculation for the ground-state energy has been performed using the truncated V8' potential, and consisting in the comparison of our results with the ones obtained by the Fermi Hypernetted Chain approach, adopting in both cases the same mean field wave functions and the same correlation functions. The results exhibited a nice agreement between the two methods. Therefore, the approach has been applied to the calculation of the ground-state energy, density and momentum distributions of 16-O and 40-Ca using the full V8' potential, finding again a satisfactory agreement with the results based on more advanced approaches where higher order cluster contributions are taken into account. It appears therefore that the cluster expansion approach can provide accurate approximations for various diagonal and non diagonal density matrices, so that it could be used for a reliable evaluation of nuclear effects in various medium and high energy scattering processes off nuclear targets. The developed approach can be readily generalized to the treatment of Glauber type final state interaction effects in inclusive, semi-inclusive and exclusive processes off nuclei at medium and high energies.

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arXiv2005

Calculations of the Exclusive Processes 2H(e,e'p)n, 3He(e,e'p)2H and 3He(e,e'p)(pn) within a Generalized Glauber Approach

The exclusive processes 2H(e,e'p)n, 3He(e,e'p)2H and 3He(e,e'p)(pn), have been analyzed using realistic few-body wave functions and treating the final state interaction (FSI) within a Generalized Eikonal Approximation (GEA), based upon the direct calculation of the Feynman diagrams describing the rescattering of the struck nucleon with the nucleons of the A-1 system. The approach represents an improvement of the conventional Glauber approach (GA), in that it allows one to take into account the effects of the nuclear excitation of the $A-1$ system on the rescattering of the struck nucleon. Using realistic three-body wave functions corresponding to the AV18 interaction, the results of our parameter free calculations are compared with available experimental data. It is found that in some kinematical conditions FSI effects represent small corrections, whereas in other kinematics conditions they are very large and absolutely necessary to provide a satisfactory agreement between theoretical calculations and experimental data. It is shown that in the kinematics of the experimental data which have been considered, covering the region of missing momentum and energy with p_m < 0.6 GeV/c and E_m < 100 MeV in the perpendicular kinematics, the GA and GEA predictions differ only by less than 3-4 %.

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arXiv2004

Time Evolution of Hadronization and Grey Tracks in DIS off Nuclei

The analysis of the grey tracks produced in Deep Inelastic Scattering (DIS) off nuclei provides important information on the space-time development of hadronization in nuclear medium. This method is complementary to the measurement of nuclear attenuation of leading inclusive hadrons. While the latter is focused on the hadronization dynamics for the quite rare process of leading hadrons production, the former covers the main bulk of inelastic events, and its Q^2 dependence is a very sensitive tool to discriminate between different models of hadronization. Employing the model of perturbative hadronization developed earlier, we calculate the Q^2 and x_{Bj} dependences of the number of collisions and relate it to the mean number of grey tracks, using an empirical relation obtained from the analysis of data from the Fermilab E665 experiment on DIS of muons off the Xe nucleus. We found the number of grey tracks to rise steeply with Q^2 in good agreement with the experimental data.

hep-ph↗
arXiv2003

Realistic Calculations of One- and Two-Hadron Emission Processes off Few- and Many-Body Nuclei

The exclusive electro-disintegration processes 2H(e,e'p)n, 3He(e,e'p)2H, 3He(e,e'p)pn, 3He(e,e'pp)n and 4He(e,e'p)3H have been calculated using realistic few-body wave functions and treating final state interaction (FSI) effects within a generalized eikonal approach. The semi-inclusive scattering A(e,e'p)X off complex nuclei has been analyzed using many-body wave functions for 16O and 40Ca, obtained within the framework of a linked cluster expansion and taking FSI into account by a Glauber-type approach. The effect of color transparency has also been included by considering the Finite Formation Time (FFT) that the hit hadron needs to reach its asymptotic physical state.

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arXiv2003

Hadronization and final state interaction effects in semi-exclusive Deep Inelastic Scattering off nuclei

Recent calculations of the effects of hadronization and final state interaction (FSI) in semi-exclusive deep-inelastic scattering (DIS) $A(e,e'(A-1))X$ processes are reviewed. The basic ingredient underlying these calculations, {\it viz} the time-dependent effective debris-nucleon cross section is illustrated, and some relevant results on complex nuclei and the deuteron are presented. In the latter case, particular attention is paid to the choice of the kinematics, for such a choice would in principle allow one to investigate both the structure function of a bound nucleon as well as the hadronization mechanisms. It is stressed that a planned experiment at Jlab on the process $D(e,e'p)X$ could be very useful in that respect.

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arXiv2003

Rescattering and finite formation time effects in electro-disintegration of the deuteron in the cumulative region

The role of rescattering due to the final state interaction (FSI) and the influence of the finite formation time (FFT) on the inclusive $D(e,e')X$ and exclusive $D(e,e'p)n$ electro-disintegration of the deuteron are studied in the cumulative kinematical region $x>1$ and moderate values of the 4-momentum transfer $Q^2=2÷10$ (GeV/c)$^2$. The spins are averaged out. It is found that in the inclusive process the relative magnitude of rescattering steadily grows with $x$ and that at $x=1.7$ it has the same order as the plane wave impulse approximation (PWIA) contribution, with the finite formation time effects decreasing the rescattering contribution by $\sim 30$%. In the exclusive process, with increasing momentum transfer, FFT substantially reduces the effects from FSI, although the latter are still appreciable in the region of momentum transfer investigated.

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arXiv2003

Realistic calculations of correlations and final state interaction effects in the A(e,e'p)X process off complex nuclei

A linked cluster expansion for the calculation of ground state observables of complex nuclei with realistic interactions has been used to calculate the ground state energy, density and momentum distribution of 16O and 40Ca. Using the same cluster expansion and the wave function and correlation parameters obtained from the energy calculation, we have evaluated the semi inclusive reaction A(e,e'p)X taking final state interaction (FSI) into account by a Glauber type approach; the comparison between the distorted and undistorted momentum distributions provides an estimate of the transparency of the nuclear medium to the propagation of the hit proton. The effect of color transparency is also included by considering the Finite Formation Time (FFT) that the hit hadron needs to reach its asymptotic physical state.

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