Investigation of Topological Features in Lepton-Number Violating Seesaw Extensions

The vacuum manifold of the Standard Model electroweak sector has a trivial homotopy group, and no topologically protected monopoles. We investigate how lepton-number–violating seesaw extensions of the electroweak theory can modify the topology of the vacuum manifold. In particular, we study how the symmetry-breaking patterns associated with such extensions introduce non-trivial homotopy groups that support topological defects such as monopoles or cosmic strings.