Action of Singular Instantons of Hawking-Turok Type

TL;DR

This paper analyzes the action contributions of singular Hawking-Turok instantons using Kaluza-Klein methods, revealing a fixed point contribution that simplifies total action calculations and questions previous constraints.

Contribution

It introduces a fixed point contribution to the action of Hawking-Turok instantons, providing a unified expression for regular and singular cases, and challenges prior constraint assumptions.

Findings

Fixed point contribution (bolt) affects instanton action.

Unified simple expression for total action.

Questions previous constraints on instantons.

Abstract

Using Kaluza-Klein technique we show that the singularity of Hawking-Turok type has a fixed point (bolt) contribution to the action in addition to the usual boundary contribution. Interestingly by adding this contribution we can obtain a simple expression for the total action which is feasible for both regular and singular instantons. Our result casts doubt on the constraint proposed by Turok in the recent calculation in which Vilenkin's instantons are regarded as a limit of certain constrained instantons.