The SG Propagator
 b = l/16m, Mn = (2n+1)m and  DF=[K2-Mn+ie)-1  is the usual Feynman Propagator in momentum space. The SG poropagator like other solitary wave propagators is essentially a superposition of Feynman propagators it has, however, the advantage of automatically exchanging  a series of massive bosons with a minimum of parameters . The sequence of bosons lead to superposition of attractive as well as repulsive Yukawa and exponential potential terms in configuration (position) space2.
2 M. Sebhatu, Nuovo Cimento A33, 508(1976);Lett. Nuovo Cim. 16, 463(1976); Lett. Nuovo Cim. 36, 513 (1986); nuc-th/9409015