Nuclear tensor force
= Nuclear tensor force
{title2=$S_{12}=3(\boldsymbol\sigma_1\cdot\hat{\mathbf r})(\boldsymbol\sigma_2\cdot\hat{\mathbf r})-\boldsymbol\sigma_1\cdot\boldsymbol\sigma_2$}
The <linear operator> $V_T(r)S_{12}$ couples <nucleon> <spin> orientations to their separation direction $\hat{\mathbf r}$. Here $\boldsymbol\sigma_i$ are <Pauli matrices>. A scalar radial <potential energy> alone omits this directional dependence.