Wormholes and flux tubes in 5D Kaluza-Klein theory

In this paper spherically symmetric solutions to 5D Kaluza-Klein theory, with ``electric'' and/or ``magnetic'' fields, are investigated. It is shown that the global structure of the spacetime depends on the relation between the ``electrical'' and ``magnetic'' Kaluza-Klein fields. For a small ``magnetic'' field we find a wormholelike solution. As the strength of the ``magnetic'' field is increased relative to the strength of the ``electrical'' field, the wormholelike solution evolves into a finite or infinite flux tube depending on the strength of the two fields. For the large ``electric'' field case we conjecture that this solution can be considered as the mouth of a wormhole, with the ${G}_{55}, {G}_{5t},$ and ${G}_{5\ensuremath{\varphi}}$ components of the metric acting as the source of the exotic matter necessary for the formation of the wormhole's mouth. For the large ``magnetic'' field case a 5D flux tube forms, which is similar to the flux tube between two monopoles in type-II superconductors, or the hypothesized color field flux tube between two quarks in the QCD vacuum.