| The exclusive reaction
gamma p -> p pi+ pi- was studied in the photon energy range 3.0 - 3.8 GeV and momentum transfer range 0.4 < −t < 1.0 GeV2. 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−1. The reaction was isolated by detecting the pi+ and proton in CLAS, and reconstructing the pi− 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 Mpi+pi− mass range 0.4−1.4 GeV were derived performing a partial wave expansion of the extracted moments. Besides the dominant contribution of the rho(770) meson in the P-wave, evidence for the f0(980) and the f2(1270) mesons was found in the S and D-waves, respectively. The differential production cross sections dsigma/dt for individual waves in the mass range of the above-mentioned mesons were extracted. This is the first time the f0(980) has been measured in a photoproduction experiment. |
