Chaichian M, Kobakhidze A B
High Energy Physics Division, Department of Physics, University of Helsinki and Helsinki Institute of Physics, FIN-00014 Helsinki, Finland.
Phys Rev Lett. 2001 Oct 22;87(17):171601. doi: 10.1103/PhysRevLett.87.171601. Epub 2001 Oct 5.
In higher dimensional theories, such as brane world models with quasilocalized non-Abelian gauge fields, the vacuum structure turns out to be trivial. Since the gauge theory behaves at large distances as a 4 + delta dimensional, thus the topology of the infinity is that of S(3+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 well there are no contributions to the straight theta term from the higher dimensional solitonic configurations. In this way, the strong CP problem is absent in the models with quasilocalized gluons.
在更高维理论中，比如具有准定域非阿贝尔规范场的膜世界模型，真空结构结果是平凡的。由于规范理论在大距离下表现为4 + δ维，因此无穷远的拓扑是S(3 + δ)的拓扑而非S(3)的拓扑。这种拓扑不支持有限作用量的瞬子构型，所以CP破坏的θ项在膜世界体积上消失。同样，更高维孤子构型对直θ项也没有贡献。这样一来，具有准定域胶子的模型中不存在强CP问题。
