487 research outputs found
y-scaling in Quasielastic Electron Scattering from Nuclei
A relativistic single particle model is used to calculate the inclusive
reaction from 12, 40, 56, 197, and 208 nuclei in the quasielastic
region. We have shown that this model provides a very good description of the
available experimental cross sections when they are dominated by the
quasielastic process. In this paper we use this model to investigate the
dependence of -scaling on electron kinematics, particularly the electron
scattering angle, for a range of squared four momentum transfer
(GeV/c). In this kinematic domain, Coulomb distortion of the electron does
not significantly affect scaling, but final state interactions of the knocked
out nucleon do affect scaling particularly when the nucleons have lower
energies. In general, we find that scaling works for this reaction, but at
lower values of the four momentum transfer, the scaling function does have some
dependence on the electron scattering angle. We also consider a modification of
y-scaling to include small binding energy effects as a function of Z and A and
show that there is some improvement in scaling.Comment: 21 pages, 11 figure
Investigation of the Neutron Form Factors by Inclusive Quasi-Elastic Scattering of Polarized Electrons off Polarized He: A Theoretical Overview
The theory of quasi-elastic inclusive scattering of polarized leptons off
polarized He is critically reviewed and the origin of different expressions
for the polarized nuclear response function appearing in the literature is
explained. The sensitivity of the longitudinal asymmetry upon the neutron form
factors is thoroughly investigated and the role played by the polarization
angle for minimizing the proton contribution is illustrated.Comment: Phys. Rev C in press; 9 figs. (available upon request
Superscaling predictions for neutrino-induced charged-current charged pion production at MiniBooNE
Superscaling approximation (SuSA) predictions to neutrino-induced
charged-current charged pion production in the \Delta-resonance region are
explored under MiniBooNE experimental conditions. The results obtained within
SuSA for the flux-averaged double-differential cross sections of the \pi+
production for the \nu_\mu+CH_2 reaction as a function of the muon kinetic
energy and of the scattering angle, the cross sections averaged over the angle,
the total cross section for the \pi+ production, as well as CC1\pi+ to CCQE
cross section ratio are compared with the corresponding MiniBooNE experimental
data. The SuSA predictions are in good agreement with data on neutrino flux
average cross-sections, but a somewhat different dependence on the neutrino
energy is predicted than the one resulting from the experimental analysis.Comment: 15 pages, 6 figures, accepted for publication in Physics Letters
Quasielastic Versus Inelastic and Deep Inelastic Lepton Scattering in Nuclei at x > 1
We have made a thorough investigation of the nuclear structure function W_2A
in the region of 0.8 < x < 1.5 and Q^2 < 20 GeV^2, separating the quasielastic
and inelastic plus deep inelastic contributions. The agreement with present
experimental data is good giving support to the results for both channels.
Predictions are made in yet unexplored regions of x and Q^2 to assert the
weight of the quasielastic or inelastic channels. We find that at Q^2 < 4 GeV^2
the structure function is dominated by the quasielastic contributions for x <
1.5, while for values of Q^2 > 15 GeV^2 and the range of x studied the
inelastic channels are over one order of magnitude bigger than the quasielastic
one. The potential of the structure function at x > 1 as a source of
information on nuclear correlations is stressed once more.Comment: 17 pages, LaTeX, 13 PostScript figures, final version to be published
in Nuclear Physics
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.Comment: 42 pages, 18 figure
Can neutron electromagnetic form factors be obtained by polarized inclusive electron scattering off polarized three-nucleon bound states?
The investigation of the electromagnetic inclusive responses of polarized
He within the plane wave impulse approximation is briefly reported. A
particular emphasys is put on the extraction, from the inclusive responses at
the quasielastic peak, of the neutron form factors from feasible experiments.Comment: 6 pages, Latex, 4 Postscript figures. Presented to XVth Conference on
"Few-body problems in Physics", Groningen July 1997.To appear in Nucl. Phys.
Many-Body Theory of the Electroweak Nuclear Response
After a brief review of the theoretical description of nuclei based on
nonrelativistic many-body theory and realistic hamiltonians, these lectures
focus on its application to the analysis of the electroweak response. Special
emphasis is given to electron-nucleus scattering, whose experimental study has
provided a wealth of information on nuclear structure and dynamics, exposing
the limitations of the shell model. The extension of the formalism to the case
of neutrino-nucleus interactions, whose quantitative understanding is required
to reduce the systematic uncertainty of neutrino oscillation experiments, is
also discussed.Comment: Lectures delivered at the DAE-BRNS Workshop on Hadron Physics.
Aligarh Muslim University, Aligarh (India), February 18-23, 200
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.Comment: 38 pages, 1 figure; changed references and text in Section I
(Introduction
- …