Concluding Remarks
I hope this presentation has demonstrated that  realistic potentials ( with a minimum number of parameters —three  or less) can be derived using  nonlinear  pion meson fields. The SG SWEP was used as an example. However, most people prefer the lF4  SWEP. It  yields almost identical results as the SG SWEP.  More general nonlinear extensions  to the Klein Gordon equation of the form l1F2p+1+l2F4p+1 exist. (See Burt’s webpage and references there in) .
Burt has found a simple  mass formula for  pseudoscalar mesons :
Mn = (3n+1)mp  n= 0, 1,2, 3… , mp is the pion mass. This formula is obtained from  the poles of the  propagator based on the equation
 ¶m¶mF+m2F+l1F5+l2F7=0. 
It will be interesting to derive and test a corresponding SWEP It may also be necessary to incorporate  r and w mesons. Vector meson can contribute the missing VLS term. The r meson can also weaken the strong pion tensor contribution. The Hamburg nuclear theory group has done all these and more. However,  they include two  fictitious s mesons. This may not be necessary. With an appropriate choice of the self interaction coupling constant(s),  SWEPs can provide sufficient intermediate attraction. Fictitious one or more  s mesons are used to simulate multi-meson exchanges in OBEPs and in OSBEPs.
Once expressions for SWEPs are derived, it is possible to involve undergraduate students in the physical sciences to do most of the work.