The linked cluster expansion technique, introduced for the calculation of ground-state properties of nuclear systems, has been applied to the calculation of diagonal and non diagonal one-and two-body density matrices of nuclei ranging... more
The linked cluster expansion technique, introduced for the calculation of ground-state properties of nuclear systems, has been applied to the calculation of diagonal and non diagonal one-and two-body density matrices of nuclei ranging from $^{3} He $ to $^{208} Pb $. The results for few-body systems agree with Variational Monte Carlo results. Diagonal and non-diagonal density matrices appear in exclusive medium energy processes as $ A (e, e'2N) X $ reactions, as well as correlation corrections in many high energy hadronic ...
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The effects of the final state interaction in slow proton production in semi inclusive deep inelastic scattering processes off nuclei, A(e,e'p)X, are investigated in details within the spectator and target fragmentation mechanisms;... more
The effects of the final state interaction in slow proton production in semi inclusive deep inelastic scattering processes off nuclei, A(e,e'p)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 p...
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The mass spectrum of heavy pseudoscalar mesons, described as quark-antiquark bound systems, is considered within the Bethe-Salpeter formalism with momentum dependent masses of the constituents. This dependence is found by solving the... more
The mass spectrum of heavy pseudoscalar mesons, described as quark-antiquark bound systems, is considered within the Bethe-Salpeter formalism with momentum dependent masses of the constituents. This dependence is found by solving the Schwinger-Dyson equation for quark propagators in rainbow-ladder approximation. Such an approximation is known to provide both a fast convergence of numerical methods and accurate results for lightest mesons.
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Summary The EMC experimental results for12C and56Fe are interpreted within the coherent density fluctuation model in which nucleon-nucleon correlations and binding effects are taken into account. The nuclear structure functions for... more
Summary The EMC experimental results for12C and56Fe are interpreted within the coherent density fluctuation model in which nucleon-nucleon correlations and binding effects are taken into account. The nuclear structure functions for values of the scale variablex near unity are calculated as well.
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The production of pseudo scalar, η, η′, and vector, ω, ρ, ϕ, mesons in NN collisions at threshold-near energies is analyzed within a covariant effective meson-nucleon theory. It is shown that a good description of cross sections and... more
The production of pseudo scalar, η, η′, and vector, ω, ρ, ϕ, mesons in NN collisions at threshold-near energies is analyzed within a covariant effective meson-nucleon theory. It is shown that a good description of cross sections and angular distributions, for vector meson production, can be accomplished by considering meson and nucleon currents only, while for pseudo scalar production an inclusion of nucleon resonances is needed. The di-electron production from subsequent Dalitz decay of the produced mesons, η′ → γγ* → γe+e- and ω → πγ* → πe+e- is also considered and numerical results are presented for intermediate energies and kinematics of possible experiments with HADES, CLAS and KEK-PS. We argue that the transition form factor ω → γ*π as well as η′ → γ*γ can be defined in a fairly model independent way and the feasibility of an experimental access to transition form factors is discussed.
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ABSTRACT An approach based on combined solutions of the Bethe-Salpeter (BS) and Dyson-Schwinger (DS) equations within the ladder-rainbow approximation in the presence of singularities is proposed to describe the meson spectrum as quark... more
ABSTRACT An approach based on combined solutions of the Bethe-Salpeter (BS) and Dyson-Schwinger (DS) equations within the ladder-rainbow approximation in the presence of singularities is proposed to describe the meson spectrum as quark antiquark bound states. We consistently implement into the BS equation the quark propagator functions from the DS equation, with and without pole-like singularities, and show that, by knowing the precise positions of the poles and their residues, one is able to develop reliable methods of obtaining finite interaction BS kernels and to solve the BS equation numerically. We show that, for bound states with masses $M < 1$ GeV, there are no singularities in the propagator functions when employing the infrared part of the Maris-Tandy kernel in truncated BS-DS equations. For $M >1 $ GeV, however, the propagator functions reveal pole-like structures. Consequently, for each type of mesons (unflavored, strange and charmed) we analyze the relevant intervals of $M$ where the pole-like singularities of the corresponding quark propagator influence the solution of the BS equation and develop a framework within which they can be consistently accounted for. The BS equation is solved for pseudo-scalar and vector mesons. Results are in a good agreement with experimental data. Our analysis is directly related to the future physics programme at FAIR with respect to open charm degrees of freedom.
The cross section and the transverse-longitudinal asymmetry A_{TL} of the three-body-break-up (3BBU) process 3He(e,e'p)pn have been calculated by a non-factorized and parameter-free approach based upon realistic few-body wave... more
The cross section and the transverse-longitudinal asymmetry A_{TL} of the three-body-break-up (3BBU) process 3He(e,e'p)pn have been calculated by a non-factorized and parameter-free approach based upon realistic few-body wave functions corresponding to the $AV18$ interaction, treating the rescattering of the struck nucleon within a generalized eikonal approximation. The results of calculations exhibit a good agreement with recent JLab experimental data and
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The exclusive process 3He(e,ep)2H has been analyzed using realistic few-body wave functions corresponding to the AV 18 interaction and treating the final state interaction (FSI) within the Eikonal Approximation to describe the multiple... more
The exclusive process 3He(e,ep)2H has been analyzed using realistic few-body wave functions corresponding to the AV 18 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 � = 0 i.e. for "negative" and large ≥ 300MeV/c values of the missing momentum.
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To solve the spinor-spinor Bethe-Salpeter equation in Euclidean space we propose a novel method related to the use of hyperspherical harmonics. We suggest an appropriate extension to form a new basis of spin-angular harmonics that is... more
To solve the spinor-spinor Bethe-Salpeter equation in Euclidean space we propose a novel method related to the use of hyperspherical harmonics. We suggest an appropriate extension to form a new basis of spin-angular harmonics that is suitable for a representation of the vertex functions. We present a numerical algorithm to solve the Bethe-Salpeter equation and investigate in detail the properties of the solution for the scalar, pseudoscalar and vector meson exchange kernels including the stability of bound states. We also compare our results to the non relativistic ones and to the results given by light front dynamics.
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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... more
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 be...
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The nuclear effects, viz. the binding of nucleons and meson exchanges, in deep inelastic scattering on the deuteron are considered in a self-consistent way within a nonrelativistic approach developed by Rosa-Clot and Testa. Starting with... more
The nuclear effects, viz. the binding of nucleons and meson exchanges, in deep inelastic scattering on the deuteron are considered in a self-consistent way within a nonrelativistic approach developed by Rosa-Clot and Testa. Starting with general equations of motion of nucleons interacting with mesons, the one-particle Schrödinger-like equation for the nucleon wave function and the deep inelastic scattering amplitude with the meson-exchange currents are obtained. Effective pion-, sigma-, and omega-meson exchanges are considered. It is found that the meson corrections only partially (about 60%) restore the energy sum-rule breaking caused by the nucleon off-mass-shell effects in nuclei. This result contradicts the prediction found in the calculation of the energy sum rule in the second order of the nucleon-meson vertex and in the static approximation.
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Inclusive and exclusive electro-disintegration of 2-H, 3-He and 4-He are calculated within an approach where, besides the final state interaction (FSI), also the finite formation time (FFT) of the hit hadron to its asymptotic physical... more
Inclusive and exclusive electro-disintegration of 2-H, 3-He and 4-He are calculated within an approach where, besides the final state interaction (FSI), also the finite formation time (FFT) of the hit hadron to its asymptotic physical state is taken into account.
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ABSTRACT
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The role of the nuclear structure effects, viz. the boundness of nucleons and Delta-isobar components, in the deep inelastic scattering of leptons on the deuteron is considered. It is shown that small admixture of the Delta-isobar... more
The role of the nuclear structure effects, viz. the boundness of nucleons and Delta-isobar components, in the deep inelastic scattering of leptons on the deuteron is considered. It is shown that small admixture of the Delta-isobar configurations to the deuteron wave function may lead to significant effects in the spin structure functions of the deuteron b {1/D} and g {1/D}(