Unquenched simulations of four-nucleon interactions
  Exploratory simulations of four-nucleon interactions are performed taking into account the dynamical effects of internal nucleon loops. The four-nucleon interactions in the isoscalar and isovector channels are described by Yukawa interactions with auxiliary scalar fields. The nucleon mass and the average field lengths of the scalar fields are determined as a function of nucleon hopping parameter and Yukawa coupling strengths. There are no problems with "exceptional configurations" at strong couplings which make quenched simulations unreliable. 
Istvan Montvay
hep-lat nucl-th