Stabilized NMSSM without Domain Walls
  We reconsider the Next to Minimal Supersymmetric Standard Model (NMSSM) as a natural solution to the $\mu$-problem and show that both the stability and the cosmological domain wall problems are eliminated if we impose a ${\cal {Z}}_2$ $R$-symmetry on the non-renormalizable operators. 
C. Panagiotakopoulos, K. Tamvakis