Diffractive $\ddot{I}•$-meson photoproduction on proton near threshold

Abstract

Photoproduction of $\ddot{I}•$-meson on protons was studied by means of linearly polarized photons at forward angles in the low-energy region from threshold to $E_{\hat{I}}^3$= 2.37 GeV. The differential cross sections at $t=-|t{|}_{min}$ do not increase smoothly as $E_{\hat{I}}^3$ increases, but show a local maximum at around 2.0 GeV. The angular distributions demonstrate that $\ddot{I}•$-mesons are photo-produced predominantly by helicity-conserving processes, and the local maximum is not likely due to unnatural-parity processes.

6 pages, error on the cross sections were corrected, accepted for publication in Phys. Rev. Lett