Formation of spin-one mesons by photon-photon fusion

We have observed the formation of two spin-one mesons in γγ fusion reactions in which one photon was highly virtual. The first, consistent with being the $J^{\mathrm{PC}}$ ${=1\mathrm{}}^{++}$ $f_1$(1285), was seen in the final state η${\pi }^{+}$ ${\pi }^{\mathrm{-}}$ (η→γγ), as was the η’(958). We have previously reported the observation of the second spin-one state, the X(1420), in the final state $K^{\pm }$ $K_S^0$ ${\pi }^{\mp }$ ($K_S^0$→${\pi }^{+}$ ${\pi }^{\mathrm{-}}$). The formation of this state, which may be the $f_1$(1420) observed in hadronic interactions, is reanalyzed using a new model and more data. We consider whether the X(1420) could be the partner of the $f_1$(1285) in the $J^{\mathrm{PC}}$ ${=1\mathrm{}}^{++}$ meson nonet. The γ${\gamma }^{\mathrm{*}}$ width of each resonance was determined in several $Q^2$ bins. Using a model due to Cahn with a ρ form factor, we obtained for the coupling parameter Γ${̃}_{\gamma \gamma }$($f_1$(1285)) the value 2.4±0.5±0.5 keV.