A Zoo of Axionic Wormholes

Understand

As was discovered some time ago by Giddings and Strominger (GS), an axion can support a wormhole geometry in the presence of a massless dilaton, as long as the dilaton coupling remains below a critical value.

• We find that when the dilaton becomes massive, the set of solutions is vastly increased: not only do solutions exist above the critical value of the coupling, but new branches of solutions with several minima in the geometry also appear.
• All of these generalised GS-like solutions possess the property that, when analytically continued, they lead to a contracting baby universe.
• We show that in addition there exist families of solutions which, upon analytic continuation, lead to expanding baby universes.