Although Weakly Interacting Massive Particles (WIMPs) are promising candidates of dark matter, null results from various experiments cast doubt on WIMPs, implying the need to search for other candidates. Ultralight scalar fi?eld is one of the other dark matter candidates that is motivated by string theory. Interestingly, if it couples with Standard Model particles, it oscillates mirrors in gravitational-wave detectors and generates detectable signals. To extract information on ultralight scalar ?field dark matter from real data as much as possible, we studied its signal's characteristics in detail and developed
a suitable data-analysis method .
As a result, we found that the morphology of the signal's spectra is characterized by the frequency dispersion of the scalar ?field in the Galaxy and the period of the detector's motion. Then, we proposed two data analysis methods for that signal: (1)Incoherent sum of the spectra and (2)Narrow band stochastic gravitational-wave background search. Finally, we estimated its detectability with our analysis methods. We found that our methods can improve the existing constraints given by ?fifth-force experiments on one of the scalar fi?eld's coupling constants by a factor of O(10) to O(100) depending on its mass. Our study also demonstrated that experiments with gravitational-wave detectors play a complementary role to the Equivalence Principle tests.
: Soichiro Morisaki and Teruaki Suyama. On the detectability of ultralight scalar fi?eld dark matter with gravitational-wave detectors. arXiv:1811.05003 [hep-ph].