problem would require a precise calculation of trinucleon observables, especially the binding energy. In order to produce a preliminary qualitative indication of the role of the force considered in this work, we evaluate the expectation value $\left\langle S\right| W\left| S\right\rangle $, where $\left| S\right\rangle$ represents the principal S-state of the trinucleon, which is the basic component of its ground state wave function.

This state is written as [@Coe+]

$$\left| S\right\rangle =S\left( {\mbox{\boldmath $\hat r$}}_{ji}\right)
\Gamma _{\frac 12t}^{\frac 12m}\left( {\sf a}\right)$$

where $S\left( {\mbox{\boldmath $r $}}_{ji}\right) $ is the spatial component and $\Gamma _{\frac 12t}^{\frac 12m}\left( {\sf a}\right) $ is the antisymmetric spin-isospin wave function with $z$-components $m$ and $t$ respectively.

The action of the tensor operators $S_{ij}$ over $\left| S\right\rangle $ results in states with orbital angular momentum different from zero. Using

$$\left[ \Gamma _{\frac 12t}^{\frac 12m}\left( {\sf a}\right) \right]
^{\dagger }{\mbox{\boldmath $\tau $}}^{(i)}\cdot {\mbox{\boldmath $\tau $}}%
^{(j)}\;{\mbox{\boldmath $\sigma $} }^{(i)}\cdot {\mbox {\boldmath $\sigma$ }%
}^{(j)}\Gamma _{\frac 12t}^{\frac 12m}\left( {\sf a}\right) =-3$$

we obtain $$\begin{aligned}
\left[ \Gamma _{\frac 12t}^{\frac 12m}\left( {\sf a}\right) \right]
^{\dagger }W^{ijk}\Gamma _{\frac 12t}^{\frac 12m}\left( {\sf a}\right)
&=&-4\left( \frac{g\mu }{2m}\right) ^4\frac m{\left( 4\pi \right) ^2}\frac{%
m_s}\mu  \nonumber \\
&&\times \left\{ \left( 1-\lambda \right) U\left( m_sr_{kj},\Lambda \right)
\left[ 