Speaker
Akifumi Chitose
(Institute for Cosmic Ray Research, University of Tokyo)
Description
Metastable cosmic strings are gathering attention as potential progenitors of stochastic gravitatioanl wave background. They result from a two-step symmetry breaking $G\to H\to 1$ with $\pi_1(H)\ne 0$ and $\pi_1(G)=0$, and decay via internal monopole-antimonopole pair creation.
Conventionally, the breaking rate has been estimated by an infinitely thin string approximation, which requires a large hierarchy between the symmetry breaking scales.
We numerically constructed a tunneling path and thus obtained a robust lower limit on the tunneling factor $e^{-S}$ even for mild scale hierarchy. In particular, it is relevant to the cosmic string interpretation of the gravitational wave signals recently reported by pulsar timing array experiments.
Authors
Akifumi Chitose
(Institute for Cosmic Ray Research, University of Tokyo)
Keiichi Watanabe
Masahiro Ibe
(Institute for Cosmic Ray Research, University of Tokyo)
Satoshi Shirai
(Kavli IPMU)
Mr
Yuhei NAKAYAMA
(The University of Tokyo)
