Measurement of η photoproduction on the proton from threshold to 1500 MeV (original) (raw)
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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.
Differential cross section measurement of η photoproduction on the proton from threshold to 1100 MeV
Physics Letters B, 2002
Measurement of the differential cross section for the reaction p(γ, ηp) is presented from threshold to 1100 MeV photon laboratory energy. The experiment has been performed using the GRAAL facility in Grenoble. For the first time, the region of the S11(1535) resonance is fully covered, allowing a precise extraction of its width. Above 900 MeV, s-wave dominance disappears while p and d-waves take over. A discussion about their origin is given, suggesting unexpected contribution from vector meson exchange or the need for "missing" resonances.
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.
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.
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].
Photoproduction of η-mesons off nuclei for Eγ⩽ 2.2 GeV
2008
Photoproduction of η mesons off 12 C, 40 Ca, 93 Nb, and nat Pb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2 GeV. The experiment was performed at the Bonn ELSA accelerator with the combined setup of the Crystal Barrel and TAPS calorimeters. It aimed at the in-medium properties of the S11(1535) nucleon resonance and the study of the absorption properties of nuclear matter for η mesons. Careful consideration was given to contributions from ηπ final states and secondary production mechanisms of η-mesons e.g. from inelastic πN reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross section σNη for η mesons is constant over a wide range of the η momentum. The comparison of the excitation functions to data off the deuteron and to calculations in the framework of a BUU-model show no unexplained in-medium modifications of the S11(1535).
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.
N ⁎ → Nη ′ decays from photoproduction of η ′ -mesons off protons
Physics Letters B
A study of the partial-wave content of the γp → η ′ p reaction in the fourth resonance region is presented, which has been prompted by new measurements of polarization observables for that process. Using the Bonn-Gatchina partial-wave formalism, the incorporation of new data indicates that the N (1895)1/2 − , N (1900)3/2 + , N (2100)1/2 + , and N (2120)3/2 − are the most significant contributors to the photoproduction process. New results for the branching ratios of the decays of these more prominent resonances to N η ′ final states are provided; such branches have not been indicated in the most recent edition of the Review of Particle Properties. Based on the analysis performed here, predictions for the helicity asymmetry E for the γp → η ′ p reaction are presented.