The $A_y$ Problem for $\mathit{p}-{}_{}{}^3{}_{}{}^{}He$ Elastic Scattering

We present evidence that numerically accurate quantum calculations employing modern internucleon forces do not reproduce the proton analyzing power, $A_y$, for $p-{}^3\mathrm{He}$ elastic scattering at low energies. These calculations underpredict new measured analyzing powers by approximately $30\%$ at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=1.20\mathrm{}\mathrm{MeV}$ and by 40% at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=1.69\mathrm{}\mathrm{MeV}$, an effect analogous to a well-known problem in $p-d$ and $n-d$ scattering. The calculations are performed using the complex Kohn variational principle and the (correlated) hyperspherical harmonics technique with full treatment of the Coulomb force. The inclusion of the three-nucleon interaction does not improve the agreement with the experimental data.