Extra dimensions and the strong CP problem - art. no. 171601

In higher dimensional theories, such as brane world models with quasilocali zed non-Abelian gauge fields, the vacuum structure turns out to be trivial. Since the gauge theory behaves at large distances as a 4 + delta dimension al, thus the topology of the infinity is that of S3+delta rather than S-3. This topology does not support finite action instantonic configurations and thus the CP violating theta term vanishes on the brane world volume. As we ll there are no contributions to the theta term from the higher dimensional solitonic configurations. In this way, the strong CP problem is absent in the models with quasilocalized gluons.