HEP Theory Journal Club

Cosmic axion strings from string theoretic axions

Jim Cline

McGill University

Axion cosmic strings can produce the dominant component of axion dark matter if the Peccei-Quinn phase transition occurs after inflation. This allows one to link the axion mass to its relic density and thereby predict the axion mass. It has been argued that QCD axions derived from string theory (which can have a natural protection mechanism against PQ-symmetry breaking effects from quantum gravity) generically cannot form axion strings, and thus would not have this advantage. Here I demonstrate a simple counterexample where the axion arises from a U(1) gauge symmetry in a warped compactification from 5D. The cosmic strings have parametrically lower tension than their conventional field theory counterparts.