Production of spin-one resonances in γγ/emph>collisions

Abstract

The decay of a $J^{\mathrm{PC}}$ ${=1\mathrm{}}^{++}$ resonance into one real and one virtual photon is studied in a qq¯ bound-state model. The decay rate is proportional to $Q^2$/$M^2$ if $Q^2$, the mass squared of the virtual photon, is small compared to $M^2$, the mass squared of the resonance. The cross section for production in $e^{+}$ $e^{\mathrm{-}}$ collisions of a resonance with $J^{\mathrm{PC}}$ ${=1\mathrm{}}^{++}$ is derived in terms of the partial width of the resonance to decay into one real and one virtual photon. The angular distributions for the three-body decays of $1^{++}$ and $1^{\mathrm{-}+}$ states produced by the two-photon process are presented.