666 research outputs found
Tagged spectator deep-inelastic scattering off the deuteron as a tool to study neutron structure
We give an overview of a model to describe deep-inelastic scattering (DIS)
off the deuteron with a spectator proton, based on the virtual nucleon
approximation (VNA). The model accounts for the final-state interactions (FSI)
of the DIS debris with the spectator proton. Values of the rescattering cross
section are obtained by fits to high-momentum spectator data. By using the
so-called "pole extrapolation method", free neutron structure functions can be
obtained by extrapolating low-momentum spectator proton data to the on-shell
neutron pole. We apply this method to the BONuS data set and find a surprising
Bjorken dependence, indicating a possible rise of the neutron to proton
structure function ratio at high .Comment: 6 pages, 4 figures, proceedings of POETIC
On the density dependence of single-proton and two-proton knockout reactions under quasifree conditions
We consider high-energy quasifree single- and two-proton knockout reactions
induced by electrons and protons and address the question what target-nucleus
densities can be effectively probed after correcting for nuclear attenuation
(initial- and final-state interactions). Our calculations refer to ejected
proton kinetic energies of 1.5 GeV, the reactions (e,e'p), (\gamma,pp) and
(p,2p) and a carbon target. It is shown that each of the three reactions is
characterized by a distinctive sensitivity to the density of the target
nucleus. The bulk of the (\gamma,pp) strength stems from the high-density
regions in the deep nuclear interior. Despite the strong attenuation, sizable
densities can be probed by (p,2p) provided that the energy resolution allows
one to pick nucleons from s orbits. The effective mean densities that can be
probed in high-energy (e,e'p) are of the order of 30-50% of the nuclear
saturation density.Comment: 10 pages, 2 figure
Final-state interactions in semi-inclusive deep inelastic scattering off the Deuteron
Semi-inclusive deep inelastic scattering off the Deuteron with production of
a slow nucleon in recoil kinematics is studied in the virtual nucleon
approximation, in which the final state interaction (FSI) is calculated within
general eikonal approximation. The cross section is derived in a factorized
approach, with a factor describing the virtual photon interaction with the
off-shell nucleon and a distorted spectral function accounting for the
final-state interactions. One of the main goals of the study is to understand
how much the general features of the diffractive high energy soft rescattering
accounts for the observed features of FSI in deep inelastic scattering(DIS).
Comparison with the Jefferson Lab data shows good agreement in the covered
range of kinematics. Most importantly, our calculation correctly reproduces the
rise of the FSI in the forward direction of the slow nucleon production angle.
By fitting our calculation to the data we extracted the and
dependences of the total cross section and slope factor of the interaction of
DIS products, , off the spectator nucleon. This analysis shows the
scattering cross section rising with and decreasing with an increase of
. Finally, our analysis points at a largely suppressed off-shell part of
the rescattering amplitude.Comment: 27 pages, 8 figures. Corrected typos, section II.E has been expanded
a bit. Figures have been updated to conform to the publication guidelines.
Results and conclusions haven't changed. Accepted for publication in PR
Nuclear rho transparencies in a relativistic Glauber model
[Background] The recent Jefferson Lab data for the nuclear transparency in
electroproduction have the potential to settle the scale for the
onset of color transparency (CT) in vector meson production.
[Purpose] To compare the data to calculations in a relativistic and
quantum-mechanical Glauber model and to investigate whether they are in
accordance with results including color transparency given that the computation
of -nucleus attenuations is subject to some uncertainties.
[Method] We compute the nuclear transparencies in a multiple-scattering
Glauber model and account for effects stemming from color transparency, from
-meson decay, and from short-range correlations (SRC) in the final-state
interactions (FSI).
[Results] The robustness of the model is tested by comparing the mass
dependence and the hard-scale dependence of the nuclear
transparencies with the data. The hard-scale dependence of the nuclear transparencies for C and Fe are only moderately
affected by SRC and by -decay.
[Conclusions] The RMSGA calculations confirm the onset of CT at four-momentum
transfers of a few (GeV/c) in meson electroproduction data. A more
precise determination of the scale for the onset of CT is hampered by the lack
of precise input in the FSI and -meson decay calculations.Comment: 18 pages, 5 figures. Revised version to appear in PRC. Minor
corrections, added discussion and figure about CT parameters dependence.
Results and conclusions remain the sam
Modeling final-state interactions with a relativistic multiple-scattering approximation
We address the issue of nuclear attenuation in nucleon and pion knockout
reactions. A selection of results from a model based on a relativistic
multiple-scattering approximation is presented. We show transparency
calculations for pion electroproduction on several nuclei, where data are in
very good agreement with calculations including color transparency. Secondly,
we discuss the density dependence of reactions involving one or double proton
knockout. The latter reaction succeeds in probing the high density regions in
the deep interior of the nucleus.Comment: 6 pages, 4 figures, "Relativistic Description of Two- and Three-Body
Systems in Nuclear Physics", ECT, October 19-13 200
Final-state interactions in deep-inelastic scattering from a tensor polarized deuteron target
Deep-inelastic scattering (DIS) from a tensor polarized deuteron is sensitive
to possible non-nucleonic components of the deuteron wave function. To
accurately estimate the size of the nucleonic contribution, final-state
interactions (FSIs) need to be accounted for in calculations. We outline a
model that, based on the diffractive nature of the effective hadron-nucleon
interaction, uses the generalized eikonal approximation to model the FSIs in
the resonance region, taking into account the proton-neutron component of the
deuteron. The calculation uses a factorized model with a basis of three
resonances with mass GeV as the relevant set of effective hadron states
entering the final-state interaction amplitude for inclusive DIS. We present
results for the tensor asymmetry observable for kinematics accessible
in experiments at Jefferson Lab and Hermes. For inclusive DIS, sizeable effects
are found when including FSIs for Bjorken , but the overall size of
remains small. For tagged spectator DIS, FSIs effects are largest at
spectator momenta around 300 MeV and for forward spectator angles.Comment: 7 pages, 3 figures, proceedings of the Tensor Polarized Solid Target
Workshop March 10-12, 2014 (Jefferson Lab, Newport News, USA
Longitudinal spin asymmetries in polarized deuteron DIS with spectator tagging
Polarized electron-deuteron DIS with spectator proton tagging offers a way of
measuring the neutron spin structure functions with maximal theoretical control
of nuclear effects. We calculate the nuclear structure factors in the
longitudinal double-spin asymmetries using methods of light-front nuclear
structure. A unique feature of the spin-1 system is that spin asymmetries can
be formed either relative to the cross section in all three spin states
() or in the two maximum-spin states only (,
involving tensor polarization). We find that the two-state deuteron spin
asymmetry at small spectator proton momenta permits accurate extraction of the
neutron structure function . Such measurements could be performed at a
future electron-ion collider (EIC) with polarized deuteron beams and suitable
forward detectors.Comment: 7 pages, 2 figures; Proceedings of 23rd International Spin Physics
Symposium (SPIN2018), 10-14 September, 2018; Ferrara, Ital
Nuclear final-state interactions in deep inelastic scattering off the lightest nuclei
We review recent progress in studies of nuclear final-state interactions in
deep inelastic scattering (DIS) off the lightest nuclei tagged by a recoil
nucleon. These processes hold a lot of potential for resolving the outstanding
issues related to the dynamics of hadronization in QCD. Within the minimal Fock
component framework, valid at large Bjorken , the main features of the
theoretical approach based on the virtual nucleon approximation are elaborated.
In this approach, the strong final-state interaction of the DIS products with
the nuclear fragments is described by an effective eikonal amplitude, whose
parameters can be extracted from the analysis of semi-inclusive DIS off the
deuteron target. The extraction of the and mass dependences of these
parameters gives a new observable in studying the QCD structure of DIS final
states. Another important feature of tagged DIS off the lightest nuclei is the
possibility of performing pole extrapolation with a high degree of accuracy.
Such extrapolation allows an extraction of the neutron structure function in a
model independent way due to suppression of the final-state interaction in the
on-shell limit of the struck nucleon propagator. We review the first
application of the pole extrapolation to recent experimental data. Finally, we
outline the extension of the framework to inclusive DIS, including a polarized
deuteron target as well as its application to the tagged DIS reactions for
future experiments at fixed target and collider energies.Comment: 36 pages, final version accepted in Int. J. Mod. Phys. E. Minor
changes in the tex
DIS on a polarized spin-1 target with spectator tagging
We discuss the process of deep-inelastic electron scattering (DIS) on the polarized deuteron with detection of a nucleon in the nuclear fragmentation region (“spectator tagging”). We cover (a) the general structure of the semi-inclusive DIS cross section on a spin-1 target; (b) the tagged structure functions in the impulse approximation, where deuteron structure is described by the NN light-front wave function; (c) the extraction of free neutron structure through on-shell ex-trapolation in the recoil proton momentum. As an application we consider the extraction of the neutron structure function F 2n and spin structure function g 1n through electron scattering on the (un)polarized deuteron with proton tagging and on-shell extrapolation. Such measurements would be possible at an Electron-Ion Collider (EIC) with polarized deuteron beams and forward proton detectors
- …