Evaluation of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>γ</mml:mi><mml:mi>n</mml:mi><mml:mo>→</mml:mo><mml:msup><mml:mi>π</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mi>p</mml:mi></mml:mrow></mml:math>differential cross section in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Δ</mml:mi></mml:math>-isobar region

Briscoe, W. J.; Kudryavtsev, A. E.; Pedroni, P.; Strakovsky, I. I.; Tarasov, V. E.; Workman, R. L.

doi:10.1103/physrevc.86.065207

Cited by 26 publications

(37 citation statements)

References 16 publications

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“…Results for quasi-free photoproduction of η and η ′ mesons off the deuteron [43,44] show no significant FSI influence at the current level of the statistical precision of the experimental data. However, results for the quasi-free γn → pπ − reaction [32,[45][46][47] found significant FSI effects, in particular for forward-meson angles. This is the kinematic regime where nucleon-nucleon FSI becomes important due to the small relative momentum between the 'participant' and 'spectator' nucleon.…”

mentioning

confidence: 95%

Photoproduction of π0 mesons off protons and neutrons in the second and third nucleon resonance regions

Dieterle¹,

Werthmüller²,

Abt³

et al. 2018

Phys. Rev. C

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Background: Photoproduction of mesons off quasi-free nucleons bound in the deuteron allows to study the electromagnetic excitation spectrum of the neutron and the isospin structure of the excitation of nucleon resonances. The database for such reactions is much more sparse than for free proton targets.Purpose: Study experimentally single π 0 photoproduction off quasi-free nucleons from the deuteron. Investigate nuclear effects by a comparison of the results for free protons and quasi-free protons. Use the quasi-free neutron data (corrected for nuclear effects) to test the predictions of reaction models and partial wave analysis (PWA) for γn → nπ 0 derived from the analysis of the other isospin channels.Methods: High statistics angular distributions and total cross sections for the photoproduction of π 0 mesons off the deuteron with coincident detection of recoil nucleons have been measured for the first time. The experiment was performed at the tagged photon beam of the Mainz MAMI accelerator for photon energies between 0.45 GeV and 1.4 GeV, using an almost 4π electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. A complete kinematic reconstruction of the final state removed the effects of Fermi motion.Results: Significant effects from final state interactions (FSI) were observed for participant protons in comparison to free proton targets (between 30% and almost 40%). The data in coincidence with recoil neutrons were corrected for such effects under the assumption that they are identical for participant protons and neutrons. Reaction model predictions and PWA for γn → nπ 0 , based on fits to data for the other isospin channels, disagreed between themselves and no model provided a good description of the new data. Conclusions:The results demonstrate clearly the importance of a mesurement of the fully neutral final state for the isospin decmposition of the cross section. Model refits, for example from the Bonn-Gatchina analysis, show that the new and the previous data for the other three isospin channels can be simultaneously described when the contributions of several partial waves are modified. The results are also relevant for the suppression of the higher resonance bumps in total photoabsorption on nuclei, which are not well understood.The photoproduction of mesons is a prime tool for the study of the excitation spectrum of the nucleon, which is a major testing ground for the properties of the strong interaction in the non-perturbative regime. The pion is the lightest meson and has a strong coupling to many nucleon excited states. Although recent years have provided new photoproduction data for many different final states, pion scattering and photoproduction of pions are still central to most analyses which aim to identify and characterize the excited states of nucleons. Many theoretical frameworks are employed to extract this information. They include the SAID multipole analysis [1,2], the MAID unitary isobar model [3,4], the Dubna-Mainz-Taipei (DMT) dynamical model [5], the Bonn-Gatchi...

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confidence: 95%

Photoproduction of π0 mesons off protons and neutrons in the second and third nucleon resonance regions

Dieterle¹,

Werthmüller²,

Abt³

et al. 2018

Phys. Rev. C

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“…Many high-precision data for the γn → π − p and γn → π 0 n reactions have been measured recently. We applied our GW-ITEP FSI corrections, covering a broad energy range up to E = 2.7 GeV [8], to the CLAS and A2 Collaboration γd → π − pp measurements to get elementary cross sections for γn → π − p [14,15]. In particular, the new CLAS cross sections have quadrupled the world database for γn → π − p above E = 1 GeV.…”

Section: Neutron Databasementioning

confidence: 99%

“…2), were done, as we did recently [8,14,15], for the CLAS [14] and MAMI data [15]. The SAID of GW Data Analysis Center (DAC) phenomenological amplitudes for γN → πN [16], NN → NN [17], Figure 1.…”

Section: Neutron Data From Deuteron Measurementsmentioning

confidence: 99%

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Radiative Decay Width of Neutral non-Strange Baryons from PWA

Strakovsky

Briscoe

Kudryavtsev

et al. 2015

EPJ Web of Conferences

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Abstract. An overview of the GW SAID and ITEP groups effort to analyze pion photoproduction on the neutron-target will be given. The disentanglement the isoscalar and isovector EM couplings of N * and Δ * resonances does require compatible data on both proton and neutron targets. The final-state interaction plays a critical role in the state-of-the-art analysis in extraction of the γn → πN data from the deuteron target experiments. It is important component of the current JLab, MAMI-C, SPring-8, ELSA, and ELPH programs.

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“…With this goal in mind, we have recently studied πN scattering, and π 0 N , ηN , π∆ and neutral vector meson photoproduction [9][10][11][12][13][14][15], obtaining several results that we briefly summarize below. In π 0 photoproduction, we used finite energy sum rules (FESR's) [13] to demonstrate that there is a good agreement between the partial wave models (PWA) for low energy amplitudes [16][17][18][19][20][21][22][23], and the Regge parametrization of the highenergy data. In η photoproduction, the PWA models are less constrained by the available low-energy data and we have shown how the high-energy data can help reducing uncertainties, specifically those related to unnatural exchanges [11,13].…”

Section: Introductionmentioning

confidence: 99%

Global analysis of charge exchange meson production at high energies

et al. 2018

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Many experiments that are conducted to study the hadron spectrum rely on peripheral resonance production. Hereby, the rapidity gap allows the process to be viewed as an independent fragmentation of the beam and the target, with the beam fragmentation dominated by production and decays of meson resonances. We test this separation by determining the kinematic regimes that are dominated by factorizable contributions, indicating the most favorable regions to perform this kind of experiments. In doing so, we use a Regge model to analyze the available world data of charge exchange meson production with beam momentum above 5 GeV in the laboratory frame that are not dominated by either pion or Pomeron exchanges. We determine the Regge residues and point out the kinematic regimes which are dominated by factorizable contributions.

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Evaluation of theγn→π−pdifferential cross section in theΔ-isobar region

Cited by 26 publications

References 16 publications

Photoproduction of π0 mesons off protons and neutrons in the second and third nucleon resonance regions

Photoproduction of π0 mesons off protons and neutrons in the second and third nucleon resonance regions

Radiative Decay Width of Neutral non-Strange Baryons from PWA

Global analysis of charge exchange meson production at high energies

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