Channel coupling inA(e→,e′N→

Abstract

The sensitivity of momentum distributions, recoil polarization observables, and response functions for nucleon knockout by polarized electron scattering to channel coupling in final-state interactions is investigated using a model in which both the distorting and the coupling potentials are constructed by folding density-dependent nucleon-nucleon effective interactions with nuclear transition densities. Elastic reorientation, inelastic scattering, and charge exchange are included for all possible couplings within the model space. Calculations for 16 O are presented for 200 and 433 MeV ejectile energies, corresponding to proposed experiments at MAMI and TJNAF, and for 12 C at 70 and 270 MeV, corresponding to experiments at NIKHEF and MIT-Bates. The relative importance of charge exchange decreases as the ejectile energy increases, but remains significant for 200 MeV. Both proton and neutron knockout cross sections for large recoil momenta, p m > 300 MeV/c, are substantially affected by inelastic couplings even at 433 MeV. Significant effects on the cross section for neutron knockout are also predicted at smaller recoil momenta, especially for low energies. Many of the response functions and polarization observables for nucleon knockout are quite sensitive to the coupling scheme, especially those which vanish in the absence of final-state interactions. Polarization transfer for proton knockout is insensitive to channel coupling, even for fairly low ejectile energies, but polarization transfer for neutron knockout retains nonnegligible sensitivity to channel coupling for energies up to about 200 MeV. The present results suggest that possible medium modifications of neutron and proton electromagnetic form factors for Q 2 > ∼ 0.5 (GeV/c) 2 can be studied using recoil polarization with relatively little uncertainty due to final-state interactions.

Parity violation and dynamical relativistic effects in(e⃗,e′N)reactions

“…7 we compare the RDWIA results with the positive-energy projected ones. The latter approach is simply known as effective momentum approximation (EMA) (see [23][24][25][26][27] for details on how the EMA approach is defined). As expected, the differences introduced by the choice of the current operator and/or gauge are much smaller within the EMA limit.…”

Dynamics of the quasielasticO16(e,e′p)reaction atFissum1, Liang2, Anderson3 et al. 2004Phys. Rev. C

“…Specific details regarding the boundary conditions may be found in Refs. [86][87][88]. The Madrid rdwia calculations [16] employ a partialwave expansion of the first-order Dirac equation, leading to a pair of coupled first-order differential equations.…”

“…[19-21, 88, 94]. The effect of spinor distortion within the Effective Momentum Approximation (EMA) has been studied by Kelly [88]. The LEA code has subsequently been upgraded to evaluate Eq.…”

Parity violation in quasielastic electron-nucleus scattering within the relativistic impulse approximation

“…5 we present the PV responses computed using the NCC2 prescription and the models: RPWIA and RMF-FSI. Additionally, in order to estimate the effect of the lower components of the nucleon wave function we present the results computed in the so-called "effective asymptotic momentum approximation" [50][51][52][53][54]. Within this approach, which is simply denoted as EMA, the nucleon wave function is reconstructed by imposing that the relation between lower and upper components is the same as the one for free spinors, that is,…”