U\left( \mu r_{ji},\Lambda \right) -G\left( \mu r_{ji},\Lambda
\right) \right] \right.  \nonumber \\
&&+\left. \cos \theta _j\lambda \frac{m_s}\mu U_1\left( \mu r_{ji},\Lambda
\right) U_1\left( m_sr_{kj},\Lambda \right) \right\}\end{aligned}$$

where $\cos \theta _j={\mbox{\boldmath $\hat r$}}_{ji}\cdot {\mbox{\boldmath$\hat r$}}_{kj}$. Using the results of [@Coe+] and neglecting the very short range function $G\left( \mu r_{ji},\Lambda \right) $ [@RI], we have

$$\begin{aligned}
\left[ \Gamma _{\frac 12t}^{\frac 12m}\left( {\sf a}\right) \right]
^{\dagger }W^{ijk}\Gamma _{\frac 12t}^{\frac 12m}\left( {\sf a}\right)
&=&-\left\{ \left( 1-\lambda \right) C_\sigma U\left( m_sr_{kj},\Lambda
\right) U\left( \mu r_{ji},\Lambda \right) \right.  \nonumber \\
&&+\left. \lambda C_S\cos \theta _jU_1\left( \mu r_{ji},\Lambda \right)
U_1\left( m_sr_{kj},\Lambda \right) \right\} ,\end{aligned}$$

where $C_\sigma $ and $C_S$ are the strength coefficients of sigma and chiral scalar respectively, given by

$$\begin{aligned}
C_\sigma &=&4\left( \frac{g\mu }{2m}\right) ^4\frac 1{\left( 4\pi \right) ^2}%
\frac{m_s}\mu m, \\
C_S &=&4\left( \frac{g\mu }{2m}\right) ^4\frac 1{\left( 4\pi \right) ^2}%
\left( \frac{m_s}\mu \right) ^2m.\end{aligned}$$

Choosing $m_s=550MeV$ and $g=13.5$, the strength coefficients become $%
C_\sigma =96MeV$ and $C_S=378MeV$.

In fig. 6 we show equipotential plots for the choices $\lambda =0$ (graph $a$) and $\lambda =1$ (graph $b$), constructed by keeping two nucleons $1\;fm$ apart and varying the position of the third one. As the plots are symmetric under rotation around the x-axes the specification of 