Revisiting the no-boundary proposal with a scalar field

Understand

Recent works have suggested that the no-boundary proposal should be defined as a sum over regular, not necessarily compact, metrics.

• We show that such a prescription can be implemented in the presence of a scalar field.
• For concreteness, we consider the model of Garay et al., in which the potential is a sum of exponentials, and which lends itself to an analytical treatment.
• Compared to the earlier implementation, we find that saddle points with unstable fluctuations can be eliminated by imposition of an appropriate regularity condition.