47 research outputs found
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 \phi=0 i.e. for "negative"
and large \geq 300MeV/c values of the missing momentum.Comment: 14 pages, 6 figure
AB responses: from bare nucleons to complex nuclei
We study the occurrence of factorization in polarized and unpolarized
observables in coincidence quasi-elastic electron scattering. Starting with the
relativistic distorted wave impulse approximation, we reformulate the effective
momentum approximation and show that the latter leads to observables which
factorize under some specific conditions. Within this framework, the role
played by final state interactions and, in particular, by the spin-orbit term
is explored. Connection with the nonrelativistic formalism is studied in depth.
Numerical results are presented to illustrate the analytical derivations and to
quantify the differences between factorized and unfactorized approaches.Comment: 26 pages, 5 figures. Improved and extended version. To be published
in Phys. Rev.
Gamow-Teller strength distributions in Xe isotopes
The energy distributions of the Gamow-Teller strength are studied for
even-even Xe isotopes with mass numbers from 124 to 142. A self-consistent
microscopic formalism is used to generate the single particle basis, using a
deformed Skyrme Hartree-Fock mean field with pairing correlations in BCS
approximation. The Gamow-Teller transitions are obtained within a quasiparticle
random phase approximation (QRPA) approach using a residual spin-isospin
interaction in the particle-hole and particle-particle channels. We then
discuss the pairing BCS treatment and the determination of the ph and pp
residual interaction coupling constants. We study the GT+ and GT- strength
distributions for the equilibrium nuclear shapes, which are an essential
information for studies of charge-exchange reactions and double-beta processes
involving these isotopes.Comment: 15 pages, 5 figures. To appear in Phys Rev
Global relativistic folding optical potential and the relativistic Green's function model
Optical potentials provide critical input for calculations on a wide variety of nuclear reactions, in particular, for neutrino-nucleus reactions, which are of great interest in the light of the new neutrino oscillation experiments. We present the global relativistic folding optical potential (GRFOP) fits to elastic proton scattering data from C-12 nucleus at energies between 20 and 1040 MeV. We estimate observables, such as the differential cross section, the analyzing power, and the spin rotation parameter, in elastic proton scattering within the relativistic impulse approximation. The new GRFOP potential is employed within the relativistic Green's function model for inclusive quasielastic electron scattering and for (anti) neutrino-nucleus scattering at MiniBooNE kinematics
Analysis of polarized 16O(e→,e′p→) observables within the relativistic distorted wave impulse approximation
15 págs.; 9 figs. ; PACS number(s): 25.30.Rw, 14.20.Gk, 24.10.Jv, 24.30.GdRecoil nucleon transferred polarization observables in coincidence quasielastic electron scattering are studied within the relativistic distorted wave impulse approximation. Results for response functions and polarization asymmetries are discussed for proton knockout from p1/2, p 3/2, and s1/2 shells in 16O. The impact of spinor distortion is examined by comparing the fully relativistic calculation with results obtained by projecting out the negative-energy components. In particular, a careful analysis of effects linked to the description of the bound and scattered relativistic nucleon wave functions is presented. The high sensitivity of some polarization observables to the dynamical enhancement of the lower components, already shown within the relativistic plane wave impulse approximation, is proven to be maintained in the relativistic distorted wave approach. Semi-relativistic approaches based on the effective momentum approximation are also studied. Finally, comparison with experimental data and a brief analysis of effects linked to medium modified form factors is presented. ©2004 American Physical SocietyThis work was partially supported by funds provided by
DGI (Spain) and FEDER funds, under Contract Nos.
BFM2002-03315, BFM2002-03562, FPA2002-04181-C04-
04, and BFM2000-0600 and by the Junta de Andalucía
(Spain) and in part by the U.S. Department of Energy under
Cooperative Research Agreement No. DE-FC02-
94ER40818. M.C.M. and J.R.V. acknowledge financial support
from the Fundación Cámara (University of Sevilla) and
the Consejería de Educación de la Comunidad de Madrid,
respectivelyPeer Reviewe
Relativistic description of 3He(e,e'p)2H
The Relativistic Distorted-Wave Impulse Approximation is used to describe the
He()H process. We describe the He nucleus within the
adiabatic hyperspherical expansion method with realistic nucleon-nucleon
interactions. The overlap between the He and the deuteron wave functions
can be accurately computed from a three-body calculation. The nucleons are
described by solutions of the Dirac equation with scalar and vector (S-V)
potentials. The wave function of the outgoing proton is obtained by solving the
Dirac equation with a S-V optical potential fitted to elastic proton scattering
data on the residual nucleus. Within this theoretical framework, we compute the
cross section of the reaction and other observables like the
transverse-longitudinal asymmetry, and compare them with the available
experimental data measured at JLab.Comment: 4 pages, 3 figures. Proceedings of the 21st European Few Body
Conference held in Salamanca (Spain) in August-September 201
Measurement of Rlt and Atl in the 4He(e,e'p)3H Reaction at pmiss of 130-300 MeV/c
We have measured the 4He(e,e'p)3H reaction at missing momenta of 130-300
MeV/c using the three-spectrometer facility at the Mainz microtron MAMI. Data
were taken in perpendicular kinematics to allow us to determine the response
function Rlt and the asymmetry term Atl. The data are compared to both
relativistic and non-relativistic calculations.Comment: To be published in the European Physical Journal