Photoproductions of f1(1285) and η′

Abstract

We investigate photoproduction of axial vector meson f 1 ð1285Þ based on the CLAS experiment γp → pf 1 ð1285Þ → pηπ þ π − using the Regge model for ρ 0 þ ω exchanges. The combined analysis of γp → pη 0 → pηπ þ π − reaction including ηð1295Þ is accompanied to evaluate the decay mode ηð1295Þ → ηπ þ π − from the potential overlap with the f 1 reaction. The predominance of ρ 0 ð770Þ exchange over the ωð782Þ with the coupling constant γρ 0 f 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 0 → ηπ þ π − and f 1 → ηπ þ 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 → pf 1 up to ffiffi ffi s p ≈ 50 GeV, playing role similar to the Pomeron in the vector meson photoproduction at high energies. Such a unique role of the virtual photon exchange similar to the f 1 case is identified up to ffiffi ffi s p ≈ 250 GeV in the γp → pπ 0 and γp → pη as well as γp → pη 0 reactions.

Exclusive $f_{1}(1285)$ meson production for energy ranges available at the GSI-FAIR with HADES and PANDA

“…The differential cross sections were measured from threshold up to a center-of-mass energy of W γp = 2.8 GeV in a wide range of production angles. The f 1 (1285) photoproduction was studied extensively from the theoretical point of view; see [17][18][19][20][21]. There, the t-channel ρ and ω exchange (either Regge trajectories or meson exchanges) is the dominant reaction mechanism for the small-t behaviour of the cross section, that is, in the forward scattering region.…”

“…As was shown in [20] other contributions, the s-channel proton-exchange term, the u-channel N(2300)-exchange term, and the contact term, are very small and can be neglected in the analysis of the CLAS data. The Primakoff effect by the virtual photon exchange in the t-channel was discussed in [21]. This mechanism is especially important in the forward region and at higher W γp energies.…”

“…In[21] a different relation for the coupling constants was used, namely g f 1 ωγ = −g f 1 ργ /3 instead of (A3). The relative sign of these couplings has physical significance in the process γp → f 1 (1285)p as the ρand ω-exchange terms interfere.…”