B. Van Overmeire

A relativistic framework to determine the nuclear transparency from A (p, 2p) reactions

Abstract A relativistic framework for computing the nuclear transparency extracted from A ( p , 2 p ) scattering processes is presented. The model accounts for the initial- and final-state interactions (IFSI) within the relativistic multiple-scattering Glauber approximation (RMSGA). For the description of color transparency, two existing models are used. The nuclear filtering mechanism is implemented as a possible explanation for the oscillatory energy dependence of the transparency. Results are presented for the target nuclei 7Li, 12C, 27Al, and 63Cu. An approximated, computationally less intensive version of the RMSGA framework is found to be sufficiently accurate for the calculation of the nuclear transparency. After including the nuclear filtering and color transparency mechanisms, our calculations are in acceptable agreement with the data.

Nuclear transparencies from photoinduced pion production

The strong interaction exhibits a strong scale dependence. At low energies, hadrons are undoubtedly the adequate degrees of freedom. The properties of nuclei can be fairly well understood in a picture in which nucleons exchange mesons. At high energies, that particular role of fermions interacting through force-carrying bosons is played by quarks and gluons. The transition energy region is a topic of current intensive research at, for example, the Thomas Jefferson National Accelerator Facility (Jefferson Lab), where hadronic matter can be studied with intense beams of real and virtual photons possessing the proper wavelengths in the femtometer and subfemtometer range. An observable commonly used to pin down the underlying dynamics of hadronic matter is the nuclear transparency to the transmission of hadrons. The nuclear transparency for a certain reaction process is defined as the ratio of the cross section per target nucleon to the one for a free nucleon. Accordingly, the transparency is a measure of the effect of the medium on the passage of energetic hadrons. It provides an excellent tool for searching for deviations from predictions of models based on traditional nuclear physics. One such phenomenon is color transparency (CT). Color transparency predicts the reduction of final state interactions (FSI) of hadrons propagating through nuclear matter in processes at high momentum transfer. Experiments have been carried out to measure nuclear transparencies in search of CT

Polarization transfer in 4 He(e,e p )a nd 16 O(e,e p) in a relativistic Glauber model

p) 15 N are computed within the relativistic multiple-scattering Glauber approximation (RMSGA). The RMSGA framework adopts relativistic single-particle wave functions and electron-nucleon couplings. The predictions closely match those of a relativistic plane-wave model indicating the smallness of the final-state interactions for polarization-transfer components. Also shortrange correlations play a modest role for the studied observables, as long as small proton missing momenta are probed in quasielastic kinematics. The predictions with free and various parametrizations for the mediummodified electromagnetic form factors are compared to the world data.

Second-order eikonal corrections for A(e,e′p)

Abstract The first-order eikonal approximation is frequently adopted in interpreting the results of A ( e , e ′ p ) measurements. Glauber calculations, for example, typically adopt the first-order eikonal approximation. We present an extension of the relativistic eikonal approach to A ( e , e ′ p ) which accounts for second-order eikonal corrections. The numerical calculations are performed within the relativistic optical model eikonal approximation. The nuclear transparency results indicate that the effect of the second-order eikonal corrections is rather modest, even at Q 2 ≈ 0.2 ( GeV / c ) 2 . The same applies to polarization observables, left–right asymmetries, and differential cross sections at low missing momenta. At high missing momenta, however, the second-order eikonal corrections are significant and bring the calculations in closer agreement with the data and/or the exact results from models adopting partial-wave expansions.

A relativistic Glauber approach to polarization transfer in He4(e→,e′p→)

Polarization-transfer components for He4(e→,e′p→)3H are computed within the relativistic multiple-scattering Glauber approximation (RMSGA). The RMSGA framework adopts relativistic single-particle wave functions and electron–nucleon couplings. The predictions with free and various parametrizations for the medium-modified electromagnetic form factors are compared to the world data.

Polarization transfer in {sup 4}He(e{sup {yields}},e{sup '}p{sup {yields}}) and {sup 16}O(e{sup {yields}},e{sup '}p{sup {yields}}) in a relativistic Glauber model

p) 15 N are computed within the relativistic multiple-scattering Glauber approximation (RMSGA). The RMSGA framework adopts relativistic single-particle wave functions and electron-nucleon couplings. The predictions closely match those of a relativistic plane-wave model indicating the smallness of the final-state interactions for polarization-transfer components. Also shortrange correlations play a modest role for the studied observables, as long as small proton missing momenta are probed in quasielastic kinematics. The predictions with free and various parametrizations for the mediummodified electromagnetic form factors are compared to the world data.

Polarization transfer in 4He(\vec{e},e'\vec{p}) and 16O(\vec{e},e'\vec{p}) in a relativistic Glauber model

p) 15 N are computed within the relativistic multiple-scattering Glauber approximation (RMSGA). The RMSGA framework adopts relativistic single-particle wave functions and electron-nucleon couplings. The predictions closely match those of a relativistic plane-wave model indicating the smallness of the final-state interactions for polarization-transfer components. Also shortrange correlations play a modest role for the studied observables, as long as small proton missing momenta are probed in quasielastic kinematics. The predictions with free and various parametrizations for the mediummodified electromagnetic form factors are compared to the world data.