Non-abelian Topological Strings and Metastable States in Linear Sigma   Model
  Non-abelian (NA) topological string defects exist in QCD with the spontaneous chiral symmetry breaking $U(N_f)_L \times U(N_f)_R \to U(N_f)_V$. Anomaly effects lead to domain walls connected to these strings. In the framework of linear sigma model we find the configuration of these defects. Also we show that in this model metastable CP violating vacuua exist. Strings as well as extended regions of metastable vacuua may form during the chiral transition which could have interesting effects. 
A. P. Balachandran (1), S. Digal (2)((1) Syracuse University, USA (2)   University of Bielefeld, Germany)