Action of singular instantons of Hawking-Turok type - art. no. 043510

Using the Kaluza-Klein technique we show that a singularity of Hawking-Turo k type has a fixed point (bolt) contribution to the action in addition to t he usual boundary contribution. Interestingly by adding this contribution r ye can obtain a simple expression for the total action which is feasible fo r both regular and singular instantons.