Speaker
Description
Dark photon is one of the cold dark matter (CDM) candidates. It is predicted in the context of high-scale inflation models and a part of string theories. However, experimental constraints for its mass range at around $O$(10--100)$\,\mu\mathrm{eV}/c^2$ have not been tight yet. The dark photon CDM is predicted to convert to a photon with a weak coupling constant ($\chi$). The frequency of the conversion photon corresponds to the CDM mass because of the energy conservation ($h\nu \simeq mc^2$), e.g., a signal at 24.2 GHz corresponds to the mass of $100\,\mu\mathrm{eV}/c^2$.
DOSUE-RR (Dark-matter Observing System for Un-Exprored Radio-Range) is a series of experiments searching for the conversion photons based on technologies matured in observations of the cosmic microwave background. Hence, $O$(10--100)$\,\mathrm{GHz}$ is our target frequency range of the conversion photon. We developed a cryogenically cooled setup for the 18--26.5 GHz observations, and we succeeded to improve the experimental sensitivity compared to previous studies.
We performed our first search for the dark photon CDM in the mass range of 74--110$\,\mu\mathrm{eV}/c^2$ with the world’s best sensitivity. In this presentation, we will present our first results. Even assuming that there is no significant signal, our constraint for $\chi$ will be tighter than them that is given by cosmological observations: $\chi < ($4--10$) \times 10^{-10}$.
| In-person participation | Yes |
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