Spin correlation parameter C$_{yy}$ of $p^{3}$\textit{He} backward elastic scattering at intermediate energy

For several decades considerable efforts have been performed to investigate the structure of the lightest nuclei at short distances between constituent nucleons. Large part of these investigations consists of studies of elastic backward proton-nucleus scattering (EBS). At present there is no theoretical model which quantitatively describes the existing data, even for the simplest reaction, \textit{pd} EBS. Recently there have been several theoretical attempts to understand the $p^{3}$\textit{He} EBS which is studied in much less detail than \textit{pd} EBS. We have measured the cross section and spin correlation parameter C$_{yy}$ of $p^{3}$\textit{He} EBS at 200,300 and 400 MeV. Experimental results are compared to theoretical predictions with two-nucleon pair exchange in the triplet and singlet spin states, pion-exchange and direct mechanism.