U-Spin Symmetry Test of the Sigma+ Baryon Electromagnetic Decay

This dissertation presents analysis for electromagnetic decay of the Sigma 0(1385) from the reaction gammap → K +Sigma*0. Also presented is the first ever measurement of the electromagnetic decay of the Sigma+(1385) from the reaction gamma p → K0Sigma*+. Both results are extracted from the g11alpha data set taken using the CLAS detector at Thomas Jefferson National Accelerator Facility. A real photon beam with a maximum energy of 3.8 GeV was incident on a liquid hydrogen target during the experiment resulting in the photoproduction of the kaon and Sigma* hyperons. Kinematic fitting is used to separate signal from background in each case. For the first time, a method to kinematically fit the neutron in the Electromagnetic Calorimeter (EC) of CLAS was performed, leading to a high statistics study of the neutron resolutions in the EC. New techniques in neutron resolution matching for Monte Carlo simulation using dynamic variable smearing are also developed. The results from the Sigma0(1385) electromagnetic decay lead to smaller statistical and systematic uncertainties than the previous measurement by Taylor et al. A U-spin symmetry test using the U-spin SU(3) multiplet representation gave a prediction for the Sigma* + → Sigma+gamma partial width and the Sigma* 0 → Λgamma partial width. The latter agrees, within the experimental uncertainties, with the prediction from U-spin symmetry, but the former reaction is much smaller than its prediction.