Analysis of recent $ \eta$ photoproduction data

Abstract

Recent data on η-meson photoproduction off a proton target in the energy range 2≤ √ s≤3 GeV are analyzed with regard to their overall consistency. Results from the ELSA and CLAS measurements are compared with predictions of a Regge model whose reaction amplitude was fixed via a global fit to pre-2000 measurements of differential cross sections and polarization observables for γp→ηp at higher energies. We find that all recent experimental results on differential cross sections for η-meson photoproduction are in good agreement with each other, except for the CLAS data from 2009. However, the latter can be made consistent with the other data at the expense of introducing an energy-dependent renormalization factor. We point out that there indications in the data for a possible excitation of baryon resonances with masses around 2.1 and 2.4 GeV.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

Fixed- t analyticity as a constraint in single-energy partial-wave analyses of meson photoproduction reactions

“…Using arguments from complex analysis (theory of functions) and probability theory, Pietarinen found a penalty function for the approximant (29) in the form…”

“…Therefore, expansion (29) may be truncated at some finite order N max . With the approximant in the form (29) and penalty function Φ in the form (30), the minimization of X 2 is a compromise between fitting the data and keeping higher coefficients in (29) small.…”

“…Observables are expressed in terms of several amplitudes (depending on spin and isospin structure of the particular process). Each of the amplitudes is represented by its own representation (29) and all coefficients are to be determined simultaneously. According to Pietarinen, one has to minimize a quadratic form…”

“…Coupled-channels approaches with K-matrix methods [25][26][27] and with meson-baryon dynamics [28] involve a series of hadronic channels, where experimental data has been measured. At higher energies, outside of the resonance region, Regge models have been successfully applied [21,29,30], and for an analytical connection between resonance and Regge regions, finite-energy sum rules have been investigated [31].…”

Combined analysis ofη′production reactions:γN→η′N,

“…[4,5]; however, with no clear identification of the source of the discrepancy (in this respect, see also Ref. [17]). For comparison, we show in Fig.…”