The ambiguity regarding the position of the $1^{-}$, $T=0\mathrm{}$ state in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ is resolved by comparing the results of the coupled-channels calculations with the recent phase shift analysis of the ${}_{}{}^3{}_{}{}^{}\mathrm{H}\mathrm{}(p,p)\mathrm{}$ scattering experiment. The experimental and theoretical evidence definitely suggest that this level occurs around 24 MeV in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and that the isospin splitting among the $1^{-}$ states is comparable to that in the $0^{-}$ and $2^{-}$ states belonging to the {${\mathrm{}\left(1s\right)\mathrm{}}^{-1\mathrm{}}p$} configuration.

[NUCLEAR REACTIONS ${}_{}{}^3{}_{}{}^{}\mathrm{H}\mathrm{}(p,p)\mathrm{}$; $E_p=1-10\mathrm{}$ MeV. Calculated ${}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ and ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ phase shifts and compared with experiment. Deduced the isospin splitting of one-particle—one-hole excitation in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$.]

• Received 22 June 1977

DOI:https://doi.org/10.1103/PhysRevC.17.406