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Aug 19 – 23, 2024
京都大学基礎物理学研究所
Asia/Tokyo timezone

Induced Domain Walls of QCD Axion, and Gravitational Waves

Aug 21, 2024, 10:15 AM
30m
パナソニックホール (京都大学基礎物理学研究所)

パナソニックホール

京都大学基礎物理学研究所

口頭発表

Speaker

Kai Murai (Tohoku University)

Description

We show that heavy axion domain walls induce domain walls of the QCD axion through a mixing between the heavy axion and the QCD axion, even when the pre-inflationary initial condition is assumed for the QCD axion. The induced domain walls arise because the effective $\theta$ parameter changes across heavy axion domain walls, shifting the potential minimum of the QCD axion. When the heavy axion domain walls collapse, the induced QCD axion domain walls collapse as well. This novel mechanism for producing the QCD axions can explain dark matter even with the axion decay constant as small as ${\cal O}(10^{9-10})$ GeV. In particular, this scenario requires domain wall collapse near the QCD crossover, potentially accounting for the stochastic gravitational wave background suggested by recent pulsar timing array observations, including NANOGrav.

Primary author

Kai Murai (Tohoku University)

Co-authors

Prof. Fuminobu Takahashi (Tohoku University) Mr Junseok Lee (Tohoku University) Prof. Wen Yin (Tokyo Metropolitan University)

Presentation materials