Omega N Scattering Length From Omega Photoproduction On The Proton Near The Threshold

Photoproduction of the omega meson on the proton has been experimentally studied near the threshold. The total cross sections arc determined at incident energies ranging from 1.09 to 1.15 GeV. The 1/2 and 3/2 spin averaged scattering length a(omega p) and effective range r(omega p )between the omega meson and proton are estimated from the shape of the total cross section as a function of the incident photon energy: a(omega p) = (-0.97 +/- 0.16) + i(0.07 +/- 0.15) fm and r(omega p) = (+2.78 +/- 0.61) + i(-0.01 +/- 0.48) fm, which suggests a repulsive force. The real and imaginary parts for a(omega p) and r(omega p) are determined separately for the first time. The details of the analysis and discussions are described in Ref. [1].