Physical Foundations of Cosmology

4.6 Beyond the Standard Model 225
In concluding this section, we would like to warn the reader that the above con-
siderations are simplified. To analyze defects in realistic theories with complicated
symmetry breaking schemes, we have to use more powerful methods which go
far beyond the scope of this book. In these theories hybrid topological defects, for
example, strings with monopoles at their ends, or string-bounded domain walls,
can exist.