Studies on the η meson production channel d+p → ³He+η

Investigations on the total and differential cross sections of the reaction d+p → ³He+η are of special interest since they differ strongly from a pure phase space behavior near threshold. Furthermore, analysis of the asymmetry factor α of the differential cross sections show a distinct effect of s- and p-wave interference with the η momentum, which can be explained by a rapid variation of the relative phase. These effects are an indication for an unexpected strong final state interaction (FSI) between η mesons and ³He nuclei which could lead to a quasi bound state of the ³Heη-system. Current investigations on high precision data at the internal fixed target experiment ANKE of the storage ring COSY, located at the Forschungszentrum Juelich in Germany, enable the extraction of additional total and differential cross sections for the η production up to an excess energy of Q=15 MeV with significantly improved accuracy, which will allow to study the behavior of the asymmetry factor α with high resolution. Recent results are presented and discussed.