Search for Dibaryon Signals by the Measurement of the Tensor Polarizationt20inπ−dpolScattering

The angular distribution of the tensor polarization $t_{20}$ in $\pi -d_{\mathrm{pol}}$ elastic scattering has been measured in the backward angular region at an incident pion energy of 138 MeV. Large oscillations have been found which are in disagreement with all theoretical calculations even when effects of the presently suggested dibaryon resonances with the assumed standard parameters are explicitly included.