Exact 1-Fermion Loop Contributions in 1+1 Dimensional Solitons

Abstract

We find solutions to the 1+1 dimensional scalar-only linear sigma model. A new method is used to compute 1-fermion loop contributions exactly and agreement with published results employing other methods is excellent. A renormalization scheme which differs from that commonly used in such calculations but similar to that required in 1+3 dimensions is also presented. We compare ``kink'' {\it versus} ``shallow bag'' solutions paying careful attention to the implications of the 1-fermion loop contributions for the stability of the former. We find that, for small fermion multiplicities, self-consistent shallow bag solutions are always more bound than their metastable kink counterparts. However, as the fermion multiplicity increases, shallow bags evolve into kinks which eventually are the only self-consistent configurations. This situation is qualitatively the same for the two renormalization schemes considered. When we construct ``baryons'', each containing three fermions, the kink configuration is typically more bound than the shallow bag when 1-fermion loop contributions are included.