Evidence for Nucleon-Resonance Excitation in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>ω</mml:mi></mml:math>-Meson Photoproduction

Ajaka, J.; Assafiri, Y.; Bouchigny, S.; Didelez, J. P.; Fichen, L.; Guidal, M.; Hourany, E.; Kouznetsov, V.; Kunne, R.; Mushkarenkov, A.; Nedorezov, V.; Rudnev, N.; Turinge, A.; Zhao, Qiang

doi:10.1103/physrevlett.96.132003

Cited by 39 publications

(51 citation statements)

References 24 publications

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“…The energy and angular dependence of the differential cross section near threshold however cannot be described with these mechanisms alone. Previous beam asymmetries from GRAAL [45], supported the significance of s-channel resonances near threshold (Fig. 8, bottom).…”

Section: Measurements Of Polarisation Observables Andsupporting

confidence: 53%

Photoproduction of Mesons

Schmieden

Клейн

2017

EPJ Web Conf.

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Abstract. B.1 is one of the experimental projects within the CRC 16. It aims at the systematic investigation of the photoproduction of mesons off nucleons in order to understand reaction mechanisms and the relevant degrees of freedom in resonance formation. Of particular interest is the photoproduction of mesons heavier than the pion and resonances involving hidden or open strangeness. Essential hardware contributions have been made to the experimental programme of the CRC 16 through tagging systems, and photon-beam polarisation and polarimetry. A new experiment has been set up within the framework of the BGO-OD collaboration. This combines a forward magnetic spectrometer with a central BGO calorimeter with charged particle recognition and identification. The BGO-OD experiment enables reconstruction of complex final states composed of both charged and neutral particles, complementary to the existing CBELSA/TAPS calorimeter which is optimised for multi-photon final states. Selected results of the 12-year CRC period are presented from both experiments.

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Section: Measurements Of Polarisation Observables Andsupporting

confidence: 53%

Photoproduction of Mesons

Schmieden

Клейн

2017

EPJ Web Conf.

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“…7 the comparison with published data is shown: open squares are from a different analysis of the GRAAL data performed by some members of the collaboration [15] for the three-pion decay channel. While present results show strong agreement within quoted errors, in the first two energy bins, larger asymmetry values are obtained by [15] at higher energies. The main difference between the two analysis procedures lies in the tracking reconstruction of the charged particles: this work fully exploits the good angular resolution provided by the multi-wire proportional chambers, which are not included in the analysis by [15].…”

Section: Resultsmentioning

confidence: 99%

“…In the past decade the study of baryon resonances has motivated several facilities to measure the ω meson differential cross section on the proton, with very high precision, in the energy region from threshold to 2.8 GeV [12][13][14][15][16]. Several theoretical interpretations attempted the extraction of resonant contributions, reaching conflicting results [17][18][19][20][21][22][23][24], but all agreeing that beam polarization observables are needed to constrain the dynamics of the ω photo-production reaction.…”

Section: Introductionmentioning

confidence: 99%

Measurement of theΣbeam asymmetry for theωphotoproduction off the proton and the neutron at the GRAAL experiment

Vegna¹,

D’Angelo²,

Bartalini³

et al. 2015

Phys. Rev. C

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We report on new measurements of the beam asymmetry for ω photo-production on proton and neutron in Hydrogen and Deuterium targets from the GRAAL collaboration. The beam asymmetry values are extracted from the reaction threshold (Eγ = 1.1 GeV in the free nucleon kinematics) up to 1.5 GeV of incoming photon energy. For the first time both the radiative and the threepion decay channels are simultaneously investigated on the free proton. Results from the two decay channels are in agreement and provide important constraints for the determination of resonant state contributions to the ω production mechanism. First experimental results on the deuteron allow the extraction of the Σ beam asymmetry on quasi-free nucleons. Comparison of the results for free and quasi-free kinematics on the proton shows a generally reasonable agreement, similar to the findings in pseudo-scalar meson photo-production reactions. For the first time measurements on quasi-free neutrons are available, showing that both the strength and the angular distributions of the beam asymmetry are sensibly different from the results on the proton target.

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“…The DCS and ω spin density matrix elements (SDME) have been measured at SAPHIR and published [1] and measured by the CLAS collaboration [4,36]. The only other observable measured is the single polarization observable, the photon beam asymmetry (PBA) Σ ω (θ, E) at GRAAL [2,3]. We have elected to also include the older π induced reaction data from threshold (∼ 1.72 GeV) to 1.764 GeV from the Nimrod synchrotron [6] and the Alvarez detector data from 1.75 GeV to 2.05 GeV [5] (in 100 MeV bins).…”

Section: Resultsmentioning

confidence: 99%

Dynamical coupled channels calculation of pion and omega meson production

Paris

2009

Phys. Rev. C

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A dynamical coupled channel approach is used to study π and ω-meson production induced by pions and photons scattering from the proton. Six intermediate channels including πN , ηN , π∆, σN , ρN , ωN are employed to describe unpolarized and polarized data. Bare parameters in an effective hadronic Lagrangian are determined in a fit to the data for πN → πN , γN → πN , π − p → ωn, and γp → ωp reactions at center-of-mass energies from threshold to W < 2.0 GeV. The T matrix determined in these fits is used to calculate the photon beam asymmetry for ω-meson production and the ωN → ωN total cross section and ωN scattering lengths.

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Evidence for Nucleon-Resonance Excitation inω-Meson Photoproduction

Cited by 39 publications

References 24 publications

Photoproduction of Mesons

Photoproduction of Mesons

Measurement of theΣbeam asymmetry for theωphotoproduction off the proton and the neutron at the GRAAL experiment

Dynamical coupled channels calculation of pion and omega meson production

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