Differential cross section measurement of η photoproduction on the proton from threshold to 1100 MeV (original) (raw)
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Measurement of η photoproduction on the proton from threshold to 1500 MeV
European Physical Journal A, 2007
Beam asymmetry and differential cross-section for the reaction γp → ηp were measured from production threshold to 1500MeV photon laboratory energy. The two dominant neutral decay modes of the η -meson, η → 2γ and η → 3π0 , were analyzed. The full set of measurements is in good agreement with previously published results. Our data were compared with three models. They all fit satisfactorily the results but their respective resonance contributions are quite different. The possible photoexcitation of a narrow state N(1670) was investigated and no evidence was found.
Measurement of η photoproduction on the proton from threshold to 1500-MeV - The European Physical Journal A, Hadrons and Nuclei, August 2007, Vol. 33, N. 2, pp. 169-184, ISSN: 1434-6001, doi: 10.1140/epja/i2007-10439-9 di O. Bartalini, V. Bellini, J. P. Bocquet, P. Calvat, M. Capogni, L. Casano, M. Castoldi, A. D'Angelo, J. P. Didelez, R. Di Salvo, A. Fantini, D. Franco, C. Gaulard, G. Gervino, F. Ghio, G. Giardina, B. Girolami, A. Giusa, M. Guidal, E. Hourany, R. Kunne, A. Lapik, P. Levi Sandri, A. Lleres, F. Mammoliti, G. Mandaglio, D. Moricciani, A. N. Mushkarenkov, V. Nedorezov, L. Nicoletti, C. Perrin, C. Randieri, D. Rebreyend, F. Renard, N. Rudnev, T. Russew, G. Russo, C. Schaerf, M. L. Sperduto, M. C. Sutera, A. Turinge, V. Vegna (2007). Abstract Beam asymmetry and differential cross section for the reaction gamma+p->eta+p were measured from production threshold to 1500 MeV photon laboratory energy. The two dominant neutral decay modes of the eta meson, eta->2g and eta->3pi0, were analyzed. The full set of measurements is in good agreement with previously published results. Our data were compared with three models. They all fit satisfactorily the results but their respective resonance contributions are quite different. The possible photoexcitation of a narrow state N(1670) was investigated and no evidence was found.
Measurement of eta photoproduction on the proton from threshold to 1500 MeV
Beam asymmetry and differential cross section for the reaction gamma+p->eta+p were measured from production threshold to 1500 MeV photon laboratory energy. The two dominant neutral decay modes of the eta meson, eta->2g and eta->3pi0, were analyzed. The full set of measurements is in good agreement with previously published results. Our data were compared with three models. They all fit satisfactorily the results but their respective resonance contributions are quite different. The possible photoexcitation of a narrow state N(1670) was investigated and no evidence was found.
EPJ Web of Conferences, 2014
Differential and total cross section measurements on η photoproduction were published by the CLAS Collaboration (M. Dugger et al., Phys.Rev.Lett.96, 062001 (2006) and M. Williams et al., Phys.Rev.C80, 045213 (2009)) for center-of-mass energies from near the threshold up to 2.84 GeV, and by the CB-ELSA-TAPS Collaboration (V. Crede et al., Phys.Rev.C80, 055202 (2009)) up to 2.36 GeV and also making a precise threshold scan of the differential cross section in the 1446 − 1527.4 MeV γ beam energy range. However, the wide information about reaction cross sections are not sufficient to understand the role of resonances involved in the process. Different theoretical works stressed the importance to have also polarization observables in order to solve the ambiguity in the choice of the parameters used in their models. We present the analysis of the η photoproduction off the proton, identifying the meson via the γγ, π 0 π 0 η, and π + π − η decay modes by using the GRAAL apparatus; and we show the preliminary GRAAL results on the beam asymmetry Σ from the threshold (1.446 GeV) up to 1.5 GeV.
Backward-angle η photoproduction from protons at E_{γ}=1.6–2.4 GeV
Physical Review C, 2009
Differential cross sections for η photoproduction off protons have been measured at E γ = 1.6 -2.4 GeV in the backward direction. A bump structure has been observed above 2.0 GeV in the total energy. No such bump is observed in η ′ , ω and π 0 photoproductions. It is inferred that this unique structure in η photoproduction is due to a baryon resonance with a large ss component which is strongly coupled to the ηN channel.
Photoproduction of η mesons off the proton for 1.24.7GeV using CLAS at Jefferson Laboratory
Physical Review C, 2020
Photoproduction cross sections are reported for the reaction γ p → pη using energy-tagged photons and the CLAS spectrometer at Jefferson Laboratory. The η mesons are detected in their dominant charged decay mode, η → π + π − π 0 , and results on differential cross sections are presented for incident photon energies between 1.2 and 4.7 GeV. These new η photoproduction data are consistent with earlier CLAS results but extend the energy range beyond the nucleon resonance region into the Regge regime. The normalized angular distributions are also compared with the experimental results from several other experiments, and with predictions of η-MAID 2018 and the latest solution of the Bonn-Gatchina coupled-channel analysis. Differential cross sections dσ/dt are presented for incident photon energies E γ > 2.9 GeV (W > 2.5 GeV), and compared with predictions which are based on Regge trajectories exchange in the t-channel (Regge models). The data confirm the expected dominance of ρ, ω vector-meson exchange in an analysis by the Joint Physics Analysis Center.
New Measurement of Σ Beam Asymmetry for η Meson Photoproduction on the Proton
Physical Review Letters, 1998
We present new S beam asymmetry data for h meson photoproduction on the proton, using a novel tagged, laser backscattered, linearly polarized photon beam up to 1.1 GeV. The data show large, positive asymmetries, at all incident photon energies. In addition to the S 11 ͑1535͒ and D 13 ͑1520͒ resonances necessary to reproduce the cross sections, P 13 ͑1720͒ and D 15 ͑1675͒ "four stars" resonances contribute to the S observable, but cannot reproduce the strong forward asymmetries measured at energies higher than 900 MeV. [S0031-9007(98)06957-9] PACS numbers: 13.60. Le, 13.88. + e, 14.40.Aq The underlying substructure of the nucleon gives rise to a rich spectrum of excited states, many of which have been associated with the baryon resonances seen in pN scattering [1] and p photoproduction. These baryon resonances and their associated gNN ء electromagnetic couplings form bench marks for models of hadron structure. Quark models have been quite successful in accounting for the masses of most observed resonances, although in some cases the electromagnetic couplings have presented more of a challenge [2].
Simultaneous photoproduction of η and π0 Mesons on the Proton - The American Physical Society, Physical Review Letters, February 2008, Vol. 100, N. 5, pp. 052003-1-052003-5, ISSN: 0031-9007, doi: 10.1103/PhysRevLett.100.052003 di J. Ajaka, Y. Assafiri, O. Bartalini, V. Bellini, S. Bouchigny, M. Castoldi, A. D'Angelo, J. P. Didelez, R. Di Salvo, M. Doring, A. Fantini, L. Fichen, G. Gervino, F. Ghio, B. Girolami, A. Giusa, M. Guidal, E. Hourany, R. Kunne, A. M. Lapik, P. Levi Sandri, D. Moricciani, A. N. Mushkarenkov, V. Nedorezov, E. Oset, C. Randieri, N. Rudnev, G. Russo, C. Schaerf, M. L. Sperduto, M. C. Sutera, A. Turinge (2008) Abstract The analysis of the γp→ηπ0p reaction has been performed using data from the GRAAL experiment. The total and differential cross sections and the beam asymmetry have been obtained from threshold up to 1.5 GeV of beam energy. The two resonances S11(1535) and Δ(1700) are expected to be excited in the intermediate states of this reaction. The results are used to test predictions based on the assumption that both resonances are dynamically generated from the meson-baryon interaction provided by chiral Lagrangians. The term involving the Δ(1700) excitation, followed by the decay into ηΔ(1232), is found to be dominant.
Simultaneous Photoproduction of η and π0 Mesons on the Proton
Physical Review Letters, 2008
The analysis of the p ! 0 p reaction has been performed using data from the GRAAL experiment. The total and differential cross sections and the beam asymmetry have been obtained from threshold up to 1.5 GeV of beam energy. The two resonances S 11 1535 and 1700 are expected to be excited in the intermediate states of this reaction. The results are used to test predictions based on the assumption that both resonances are dynamically generated from the meson-baryon interaction provided by chiral Lagrangians. The term involving the 1700 excitation, followed by the decay into 1232, is found to be dominant.