Let us look closer at specific partial waves for which one-pion exchange is applicable. If we have \( S=0 \) and \( T=0 \), the orbital momentum has to be an odd number in order for the total anti-symmetry to be obeyed. For \( S=0 \), the tensor force component is zero, meaning that the only contribution is $$ V_{\pi}(\mathbf{r})=\frac{3f_{\pi}^{2}}{4\pi m_{\pi}^{2}}\frac{e^{-m_\pi r}}{m_\pi r}, $$ since \( \langle\mathbf{ \sigma}_1\cdot\mathbf{ \sigma}_2\rangle=-3 \), that is we obtain a repulsive contribution to partial waves like \( ^1P_0 \).