Macroscopically large antimatter regions in the baryon asymmetric   universe
  The existence of macroscopic regions with antibaryon excess in the matter - dominated Universe is a possible consequence of the evolution of baryon charged, pseudo - Nambu - Goldstone field with lepton number violating couplings. Such regions can survive the annihilation with surrounding matter only in the case if their sizes exceeds the critical surviving size. The evolution of survived antimatter - regions with high original antibaryon density inside results in the formation of globular clusters, which is made out from antimatter stars. The origin of antimatter regions in the chosen scenario is accompanied the formation of closed domain walls, which can collapse into massive black holes deposed inside the high density antimatter regions. This fact can give us an additional hint, that an anti - stars globular cluster could be one of the collapsed - core star clusters, which populate our galaxy. 
Alexander Sakharov, Maxim Khlopov and Sergei Rubin