From a study of experimental phase shifts for $p$ + ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ elastic scattering at proton energies below 50 MeV we conclude that small $D$-state admixtures to the dominant $S$-state configuration exist in the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ ground state. This result is obtained by evaluating a forward dispersion relation for the $p$ + ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ spin-flip scattering amplitude.

• Received 9 December 1974

DOI:https://doi.org/10.1103/PhysRevLett.34.830