Photoproductions of $f_1(1285)$ and $η'(958)$ from the analysis of CLAS data with the Primakoff effect at high energies

Abstract

We investigate photoproduction of axial vector meson $f_1(1285)$ based on the CLAS experiment $γp\to pf_1(1285)\to pηπ^+π^-$ using the Regge model for $ρ^0+ω$ exchanges. The combined analysis of $γp\to pη'\to pηπ^+π^-$ reaction including $η(1295)$ is accompanied to evaluate the decay mode $η(1295)\to ηπ^+π^-$ from the potential overlap with the $f_1$ reaction. The predominance of $ρ^0(770)$ exchange over the $ω(782)$ with the coupling constant $γρ^0f_1$ extracted from the CLAS experiment leads to a good description of the measured cross sections for $f_1$, while the scale of the cross section is corrected by the branching fraction $η'\toηπ^+π^-$, and $f_1\toηπ^+π^-$, respectively. As an extension to study the nonmesonic production mechanism, the Primakoff effect by the virtual photon exchange is investigated in the exclusive reaction $γp\to pf_1$ up to $\sqrt{s}\approx50$ GeV, finding that it plays a similar role to the Pomeron in the vector meson photoproduction at high energies. Such an unique role of the virtual photon exchange similar to the $f_1$ case is identified up to $\sqrt{s}\approx250$ GeV in the $γp\to pπ^0$ and $γp\to pη$ as well as $γp\to pη'$ reaction.