Kavli Affiliate: Satoshi Shirai
| First 5 Authors: Akifumi Chitose, Akifumi Chitose, , ,
| Summary:
Cosmic strings are predicted in various extensions of the Standard Model,
including grand unified theories. Depending on the symmetry-breaking pattern,
they can be either topologically stable or metastable. Intriguingly, metastable
strings have been proposed as a possible origin of the gravitational wave (GW)
background observed by recent pulsar timing array experiments. When metastable
strings decay, they fragment into segments with monopoles and antimonopoles
attached at their endpoints. The monopole and antimonopole are strongly pulled
by the string tension. Violent oscillations of these segments have been
considered as a potential GW source, in addition to contributions from string
loops. We show that, in realistic situations, the monopoles frequently collide
with thermal fluctuations on the string segments, which act as a resistance and
prevent the oscillation. As a result, we find that the contribution from string
segments to the GW background is negligible.
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