Regge analysis and dual absorptive model for γN → πoN, γN → ηN and related processes

Argyres, E.N.; Contogouris, A.P.; Ray, S.; Svec, M.

doi:10.1016/0550-3213(72)90169-1

Cited by 10 publications

(2 citation statements)

References 33 publications

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“…Information about the relative contributions of the isovector ρ (and b 1 ) exchange and the isoscalar ω exchange amplitudes can be obtained by comparing the differential cross sections for π 0meson photoproduction on neutrons and on protons [25,75,76,77]. For the proton target the total reaction amplitude is given by the sum of the isovector and isoscalar contributions, while for the neutron target it is given by their difference.…”

Section: Total Cross Sections and The Ratio Of π 0 Photoproduction On...mentioning

confidence: 99%

Neutral pion photoproduction at high energies

et al. 2009

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A Regge model with absorptive corrections is employed in a global analysis of the world data on the reactions γp→π 0 p and γn→π 0 n for photon energies from 3 to 18 GeV. In this region resonance contributions are expected to be negligible so that the available experimental information on differential cross sections and single-and double polarization observables at −t≤2 GeV 2 allows us to determine the non-resonant part of the reaction amplitude reliably. The model amplitude is then used to predict observables for photon energies below 3 GeV. A detailed comparison with recent data from the CLAS and CB-ELSA Collaborations in that energy region is presented. Furthermore, the prospects for determining the π 0 radiative decay width via the Primakoff effect from the reaction γp→π 0 p are explored. PACS. 11.55.Jy Regge formalism -13.60.Le Meson production -13.60.-r Photon and charged-lepton interactions with hadrons -25.20.Lj Photoproduction reactions

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Section: Total Cross Sections and The Ratio Of π 0 Photoproduction On...mentioning

confidence: 99%

Neutral pion photoproduction at high energies

et al. 2009

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“…It is known [30] that polarization data constitute a rather crucial test for models based on Regge phenomenology. Indeed, all model calculations [36,37] available at the time when the experiments were published failed to reproduce the data on the beam asymmetry. The most recent analysis [22] of the γp→pη reaction is based on a Regge model proposed in 1970 [23] and considers only differential cross sections at photon energies above 4 GeV, but no polarization data.…”

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confidence: 99%

Primakoff effect in $ \eta$ -photoproduction off protons

et al. 2010

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Abstract. We analyse data on forward η-meson photoproduction off a proton target and extract the η→γγ decay width utilizing the Primakoff effect. The hadronic amplitude that enters into our analysis is strongly constrained because it is fixed from a global fit to available γp → pη data for differential cross-sections and polarizations. We compare our results with present information on the two-photon η-decay from the literature. We provide predictions for future PrimEx experiments at Jefferson Laboratory in order to motivate further studies.The decay of the light pseudoscalar mesons into two photons is related to symmetry breaking through the axial vector anomaly and reveals one of the fundamental properties of QCD [1][2][3][4][5][6][7][8]. The Adler-Bell-Jackiw (ABJ) anomaly [1,2] allows to determine the decay constant of those pseudoscalar mesons from the two-photon decay width (invoking a smooth extrapolation from the chiral limit to the physical light quark masses). While this is indeed feasible for the π 0 -meson, the situation is more complicated for the η-meson since the extrapolation from the η-mass to zero and the dominance of the ABJ anomaly is debatable. Moreover, for the η and η mesons the decay constants [9] alone do not determine the two-photon decay widths uniquely. It is necessary to know in addition the singlet-octet mixing angle.In an extension of chiral perturbation theory including the η meson -from now on called the Extended Effective Theory (EET)-the evaluation of the η → γγ decay width requires a proper mixing of the SU (3) pseudoscalar singlet and octet states so that [10]Here, f 0 η and f 8 η are the singlet and octet decay constants, θ P is the mixing angle, and α is the fine structure constant. To estimate the η → γγ radiative decay width we take from ref. Experimentally, the η → γγ decay width was determined through the QED process e + e − → e + e − η and also from measurements of the Primakoff effect with nuclear targets. The results from these two classes of experiments are in conflict [12]. While all of the QED results [13][14][15][16][17][18] are in line with eq. (2) within the experimental error, the Primakoff measurements [19,20] agree with the EET only within three times the experimental error bars, say. It was argued [21] that most of the uncertainties in the evaluation from the Primakoff effect are due to the nuclear response. Recently, it was shown [22] that the η → γγ results might depend significantly on contributions from incoherent η-meson photoproduction off nuclei.The Primakoff measurements [23] on a proton target are not included in the list of the PDG [12,21], although the quality of these data, collected at DESY, is comparable or even better than the results obtained with nuclear targets [19,20]. These data were considered [24] as a strong motivation for further η → γγ Primakoff studies [25] at JLab, however, so far they were not used explicitely for an extraction of the two-photon decay width.

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Vector-meson dominance and the mass dependence of Ball’s invariant amplitudes

Svec

1973

Lett. Nuovo Cimento

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Regge analysis and dual absorptive model for γN → πoN, γN → ηN and related processes

Cited by 10 publications

References 33 publications

Neutral pion photoproduction at high energies

Neutral pion photoproduction at high energies

Primakoff effect in $ \eta$ -photoproduction off protons

Vector-meson dominance and the mass dependence of Ball’s invariant amplitudes

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