Precision Measurements of the Electromagnetic Properties of Light Pseudoscalar Mesons at JLAB via the Primakoff Effect

Photoproductions of f1(1285) and η′Yu1, Kong2 2020Phys. Rev. D2030View full textAdd to dashboardCite

“…Pseudoscalar meson photoproduction is a typical reaction to observe the Primakoff effect by the γ Ã exchange [19,20]. A precise measurement of the Primakoff effect has been advocated to test the nonperturbative QCD based on the flavor mixing of the chiral symmetry [21]. Here, we shall reproduce the Primakoff effect in the photoproduction of π 0 and η as well as η 0 in the PrimEx energy region [21] and compare the result with the data available.…”

“…This is the so-called the Primakoff effect, which is observed at very forward angles, in general, in the photoproduction of charge-neutral meson of C-parity even [19,20]. The Primakoff effect provides an opportunity to test nonperturbative properties of QCD through the mixing of the nonet members in the axial anomaly [21]. Moreover, as the virtual photon exchange is not to be Reggeized, it is not subject to the energy dependence s αð0Þ−1 at high energies.…”

“…Nevertheless, since the exchange of the virtual photon is not to be Reggeized, its role could become significant at high energy, where there is decrease of vector meson exchange according to the energy dependence of approximately s α V ð0Þ−1 . Now that the Primakoff effect in the photoproduction of η and of η 0 is related to the flavor mixing of η-η 0 (the theme of the PrimEx project at CLAS [21] and the current upgrade to GlueX at CLAS12), measurements of the Primakoff effect in the reaction can give clues to understanding the structure of the flavor symmetry, e.g., the mixing of flavor octet and singlet between η-η 0 , and so is the mixing between f 1 ð1285Þ and f 1 ð1420Þ [22]. This point will be addressed in the context of the two-gamma decay in the photoproduction of pseudoscalar meson π 0 , η, and η 0 and will be extended to the Primakoff effect in the γp → pf 1 reaction at high energies.…”

Forward-angle incoherent photoproduction of pseudoscalar mesons off nuclei

“…[3]. For the case of η photoproduction, we expect to show the potentialities of the MCMC model for the delineation of the inelastic background in future experiments dedicated for the chiral anomaly of QCD via the Primakoff method [11], and also the prospects to extract the in-medium ηN cross section via nuclear measurements.…”

“…For the case of η photoproduction, the absence of data for k 6 GeV at extreme forward angles makes it difficult to unambiguously extract the fitted parameters with the desired accuracy. We expect that further measurements on the proton will significantly improve this deficiency [11].…”