Photoproduction of {pi}{sup +}{pi}{sup -} meson pairs on the proton

The exclusive reaction {gamma}p{yields}p{pi}{sup +}{pi}{sup -} was studied in the photon energy range 3.0-3.8 GeV and the momentum transfer range 0.4<-t<1.0 GeV{sup 2}. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range, the integrated luminosity was about 20 pb{sup -1}. The reaction was isolated by detecting the {pi}{sup +} and proton in CLAS, and reconstructing the {pi}{sup -} via the missing-mass technique. Moments of the di-pion decay angular distributions were derived from the experimental data. Differential cross sections for the S, P, and D-waves, in the M{sub {pi}{sup +}}{sub {pi}{sup -}} mass range 0.4-1.4 GeV, were derived performing a partial wave expansion of the extracted moments. Beside the dominant contribution of the {rho}(770) meson in the P-wave, evidence for the f{sub 0}(980) and the f{sub 2}(1270) mesons was found in the S and D-waves, respectively. The differential production cross sections d{sigma}/dt for individual waves in the mass range of the above-mentioned mesons were extracted. This is the first time the f{sub 0}(980) has been measured in a photoproduction experiment.