Observing invisible axions with gravitational waves
Observing invisible axions with gravitational waves
复制标题
DOI：
10.1088/1475-7516/2021/06/034
复制
发表时间：
2021-06-01
影响因子：
6.4
通讯作者：
Nicolaescu, Horia
中科院分区：
文献类型：
--
作者：
Gorghetto, Marco;Hardy, Edward;Nicolaescu, Horia
如果与轴子相关的佩切-奎因对称性在暴胀后得以恢复，轴子弦不可避免地会对随机引力波背景产生贡献。结合有效场论分析与数值模拟，我们表明，由此产生的引力波谱具有对数偏差的尺度不变形式的振幅，在低频显着增强。因此，衰变常数大于10（14）GeV且质量在10（-18）eV到10（-28）eV之间的单个超轻类轴子粒子导致可观测的引力波谱，并且与暗物质过量产生、等曲率和暗辐射对后暴胀情景的约束相容。由于频谱在很宽的频率范围内延伸，因此所产生的信号可以通过多次实验检测到。我们描述了直接的方法，在这种衰变常数膨胀后，可以恢复Peccei-Quinn对称性。根据我们的结果，我们还评论了最近可能的NANOgrav信号。
If the Peccei-Quinn symmetry associated to an axion has ever been restored after inflation, axion strings inevitably produce a contribution to the stochastic gravitational wave background. Combining effective field theory analysis with numerical simulations, we show that the resulting gravitational wave spectrum has logarithmic deviations from a scale invariant form with an amplitude that is significantly enhanced at low frequencies. As a result, a single ultralight axion-like particle with a decay constant larger than 10(14) GeV and any mass between 10(-18) eV and 10(-28) eV leads to an observable gravitational wave spectrum and is compatible with constraints on the post-inflationary scenario from dark matter overproduction, isocurvature and dark radiation. Since the spectrum extends over a wide range of frequencies, the resulting signal could be detected by multiple experiments. We describe straightforward ways in which the Peccei-Quinn symmetry can be restored after inflation for such decay constants. We also comment on the recent possible NANOgrav signal in light of our results.