Studies of η' p photoproduction at the BGOOD experiment

Abstract

Recent beam asymmetry measurements indicate a narrow resonance hidden directly at threshold in Eta' photoproduction off the proton. To date these results have not been confirmed. The BGOOD experiment at the Electron-Stretcher-Anlage (ELSA) at the University of Bonn offers a unique setup for the analysis of the Photon-Proton to Eta'-Proton reaction, consisting of a high resolution forward spectrometer and a central calorimeter. At threshold the whole range of polar angles in the center-of-mass frame is boosted into a narrow forward cone in the lab frame. Thus the recoil proton can be detected in the forward spectrometer, which offers high momentum and angular precision. Eta' decay products are detected in the central calorimeter. <br /> The basis of the analysis in this thesis is the proton reconstruction in the forward direction, i.e. in the forward spectrometer. In principle, this fully determines the reaction kinematics, given the two-body final state and the known initial state. Nevertheless, the reaction was also reconstructed with increasing levels of exclusiveness, using in part the Eta' to Pi0-Pi0-Eta and, fully exclusive, the Eta' to Photon-Photon decay modes. This is important to understand possible backgrounds in the inclusive reconstruction methods. <br /> For the investigated reconstruction methods, the necessary amount of data is estimated to achieve a statistical precision sufficient to detect the expected impact of the hypothetical narrow resonance also in the differential cross section of the Photon-Proton to Eta'-Proton reaction and discriminate between descriptions with and without said resonance. Based on the findings of this thesis, recommendations for future analyses and beam times are made.