Theoretical description of dipole resonances in 46Ti, 48Ti, 50Ti, 48Ca, 40Ca was performed. The distribution of the “hole” among the states of final nuclei was taken into account using information on ...pick-up reactions. The obtained results are in reasonable agreement with experimental data.
Methods for extracting nucleon resonance parameters from experimental data are reviewed. The formalism for the description of exclusive reactions of meson photo- and electroproduction off nucleons is ...discussed. Recent experimental data on exclusive meson production in the scattering of electrons and photons off protons are analyzed.
The single-differential and fully integrated cross sections for quasifree \(\pi^{+}\pi^{-}\) electroproduction off protons bound in deuterium have been extracted for the first time. The experimental ...data were collected at Jefferson Laboratory with the CLAS detector. The measurements were performed in the kinematic region of the invariant mass \(W\) from 1.3 to 1.825 GeV and the photon virtuality \(Q^{2}\) from 0.4 to 1.0 GeV\(^2\). Sufficient experimental statistics allowed for narrow binning in all kinematic variables, while maintaining a small statistical uncertainty. The extracted cross sections were compared with the corresponding cross sections off free protons, which allowed us to obtain an estimate of the contribution from events in which interactions between the final-state hadrons and the spectator neutron took place.
This study examines the influence of the following five factors on missing mass distributions, radiative effects, admixtures from other channels, detector resolution, Fermi smearing, and final state ...interactions with spectator nucleons. All factors are considered independently of each other. The examination is supported by theoretical calculations and exemplified by distributions of the quantities \(M^{2}_{X0}\) and \(M^{2}_{X\pi^{-}}\) that are produced by the Monte Carlo simulation for the double-pion electroproduction off protons. The study also includes a naive modeling of kinematic effects of final state interactions with spectator nucleons.
This study introduces common parameterizations of the quasi-elastic peak in the electron scattering spectrum off deuterium and provides the comparison of the parameterized cross sections with ...published experimental data. The comparison is performed in the wide \(Q^{2}\) range from \(\sim\)0.3 GeV\(^{2}\) to \(\sim\)4 GeV\(^{2}\). In this way the performance of the parameterizations and their ability to describe experimental measurements are impartially tested and the conclusion on the description reliability is made.
A new TWOPEG-D version of the event generator TWOPEG was developed. This new version simulates the quasi-free process of double-pion electroproduction off the proton that moves in the deuteron ...target. The underlying idea is the equivalence of the moving proton experiment performed with fixed laboratory beam energy to the proton at rest experiment conducted with effective beam energy different from the laboratory one. This effective beam energy differs event by event and is determined by the boost from the Lab system to the proton rest frame. The Fermi momentum of the target proton is generated according to the Bonn potential. The specific aspects of the deuteron target data analysis are discussed. The plots that illustrate the performance of TWOPEG-D are given. The link to the code is provided. The generator was tested in the analysis of the CLAS data on electron scattering off the deuteron target.
Phys. Rev. C 98, 025203 (2018) New results on the single-differential and fully-integrated cross sections
for the process $\gamma_{v} p \rightarrow p' \pi^{+} \pi^{-}$ are presented.
The experimental ...data were collected with the CLAS detector at Jefferson
Laboratory. Measurements were carried out in the kinematic region of the
reaction invariant mass $W$ from 1.3 to 1.825 GeV and the photon virtuality
$Q^2$ from 0.4 to 1.0 GeV$^2$. The cross sections were obtained in narrow
$Q^{2}$ bins (0.05 GeV$^{2}$) with the smallest statistical uncertainties
achieved in double-pion electroproduction experiments to date. The results were
found to be in agreement with previously available data where they overlap. A
preliminary interpretation of the extracted cross sections, which was based on
a phenomenological meson-baryon reaction model, revealed substantial relative
contributions from nucleon resonances. The data offer promising prospects to
improve knowledge on the $Q^{2}$-evolution of the electrocouplings of most
resonances with masses up to $\sim$1.8 GeV.
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