478 research outputs found
Polarized proton structure in the resonance region
In view of the precise data available on inclusive polarized electron
scattering off polarized proton targets in the nucleon resonance excitation
region, we compare these results with the coherent sum of resonant
contributions to the polarized structure function and virtual photon
asymmetry . To this goal, we employ the nucleon resonance
electroexcitation amplitudes determined for photon virtualities 5.0
GeV from analyses of the CLAS data on exclusive electroproduction off
protons in the resonance region. Most of the well established resonances of
four star PDG status in the mass range up to 1.75~GeV are included. We find
that the resonance-like structures observed in the inclusive data are
related to the resonant contributions in the entire range of photon virtuality
where the data on are available. In the range of invariant mass of
the final hadron system 1.5 GeV, the data on the asymmetry are
well reproduced even when accounting for resonant contributions only,
especially for the larger values of and energies analysed. This
observation offers an interesting hint to quark-hadron duality seen in
polarized inclusive electron scattering observables.Comment: Contribution to proceedings: Emergence and Structure of Baryons -
Selected Contributions from the International Conference Baryons 202
Phenomenological analysis of the CLAS data on double charged pion photo and electro- production
First comprehensive data on the evolution of nucleon resonance photocouplings
with photon virtuality Q^2 are presented for excited proton states in the mass
range from 1.4 to 2.0 GeV. N^* photocouplings were determined in
phenomenological analysis of CLAS data on 2 pi photo and electroproduction
within the framework of the JLAB-MSU phenomenological model.Comment: 10 pages, 7 figures (encapsulated postscript
Nucleon resonance contributions to unpolarised inclusive electron scattering
The first CLAS12 experiments will provide high-precision data on inclusive
electron scattering observables at a photon virtuality ranging from 0.05
GeV to 12 GeV and center-of-mass energies up to 4 GeV. In view of
this endeavour, we present the modeling of the resonant contributions to the
inclusive electron scattering observables. As input, we use the existing CLAS
electrocoupling results obtained from exclusive meson electroproduction data
off protons, and evaluate for the first time the resonant contributions based
on the experimental results on the nucleon resonance electroexcitation. The
uncertainties are given by the data and duly propagated through a Monte Carlo
approach. In this way, we obtain estimates for the resonant contributions,
important for insight into the nucleon parton distributions in the resonance
region and for the studies of quark-hadron duality
Nucleon Resonance Structure from CLAS and CLAS12 Experiments
The recent results on the photo- and electrocouplings extraction from the reaction of one- and two-pion photo- and electroproduction off protons in the resonances region are presented. The production of two charged pions is of particular importance for evaluation of the photocouplings for the Δ(1620)12 −, Δ(1700)32 −
Study of nucleon resonances with electromagnetic interactions
Recent developments in using electromagnetic meson production reactions to
study the structure of nucleon resonances are reviewed. Possible future works
are discussed.Comment: 25 pages, 19 figure
Toward a Generative Modeling Analysis of CLAS Exclusive 2 Photoproduction
AI-supported algorithms, particularly generative models, have been successfully used in a variety of different contexts. This work employs a generative modeling approach to unfold detector effects specifically tailored for exclusive reactions that involve multiparticle final states. Our study demonstrates the preservation of correlations between kinematic variables in a multidimensional phase space. We perform a full closure test on two-pion photoproduction pseudodata generated with a realistic model in the kinematics of the Jefferson Lab CLAS g11 experiment. The overlap of different reaction mechanisms leading to the same final state associated with the CLAS detector’s nontrivial effects represents an ideal test case for AI-supported analysis. Uncertainty quantification performed via bootstrap provides an estimate of the systematic uncertainty associated with the procedure. The test demonstrates that GANs can reproduce highly correlated multidifferential cross sections even in the presence of detector-induced distortions in the training datasets, and provides a solid basis for applying the framework to real experimental data
Quasi-elastic and inelastic inclusive electron scattering from an oxygen jet target
The results of an experiment on inclusive electron scattering from an oxygen
jet target, performed in a wide range of energy and momentum transfer covering
both quasi-elastic and (1232) resonance regions, are reported. In the
former region the theoretical predictions, obtained including effects of
nucleon-nucleon correlations in both initial and final states, give a good
description of the experimental data. In the inelastic region a broadening as
well as a damping of the resonant part of the cross section with respect to the
free nucleon case is observed. The need of more detailed calculations including
nuclear structure effects on the electroproduction cross section of nucleon
resonances is highlighted.Comment: to appear in Nucl. Phys.
Evidence for the Nucleon Resonance from Combined Studies of CLAS Photo- and Electroproduction Data
The analysis of the nine 1-fold differential cross sections for the
photo- and electroproduction reactions
obtained with the CLAS detector at Jefferson Laboratory was carried out with
the goal to establish the contributing resonances in the mass range from
1.6~GeV to 1.8~GeV. In order to describe the photo- and electroproduction data
with -independent resonance masses and hadronic decay widths in the
range below 1.5~GeV, it was found that an state is required
in addition to the already well-established nucleon resonances. This work
demonstrates that the combined studies of photo- and
electroproduction data are vital for the observation of this resonance. The
contributions from the state and the already established
state with a mass of 1.745~GeV are well separated by their
different hadronic decays to the and final states and the
different -evolution of their photo-/electroexcitation amplitudes. The
state is the first recently established baryon resonance for
which the results on the -evolution of the photo-/electrocouplings have
become available. These results are important for the exploration of the nature
of the ``missing'' baryon resonances.Comment: accepted for publication in Phys. Lett.
Beam-Recoil Transferred Polarization in K+Y Electroproduction in the Nucleon Resonance Region with CLAS12
Beam-recoil transferred polarizations for the exclusive electroproduction of K + Λ and K + Σ0 final states from an unpolarized proton target have been measured using the CLAS12 spectrometer at Jefferson Laboratory. The measurements at beam energies of 6.535 and 7.546 GeV span the range of four-momentum transfer Q2 from 0.3 to 4.5 GeV2 and invariant energy W from 1.6 to 2.4 GeV, while covering the full center-of-mass angular range of the K+. These new data extend the existing hyperon polarization data from CLAS in a similar kinematic range but from a significantly larger dataset. They represent an important addition to the world data, allowing for better exploration of the reaction mechanism in strangeness production processes, for further understanding of the spectrum and structure of excited nucleon states, and for improved insight into the strong interaction in the regime of nonperturbative dynamics
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