Some exact solutions of reduced scalar Yukawa theory
  The scalar Yukawa model, in which a complex scalar field interact via a real scalar field, is reduced by using covariant Green functions. It is shown that exact few-particle eigenstates of the truncated QFT Hamiltonian can be obtained in the Feshbach-Villars formulation if an unorthodox "empty" vacuum state is used. Analytic solutions for the two-body case are obtained for massless chion exchange in 3+1 dimensions and for massive chion exchange in 1+1 dimensions. Comparison is made to ladder Bethe-Salpeter, Feynman-Schwinger and quasipotential results for massive chion exchange in 3+1. Equations for the three-body case are also obtained. 
Jurij W. Darewych (York University, Toronto, Canada)