Search for the axion dark matter in the mass range of 6.62 - 6.82 µeV

Abstract

The axion is a hypothetical particle associated with the spontaneous symmetry breaking of the U(1) symmetry, proposed by Pecci and Quinn to resolve the Charge-Parity (CP) problem in quantum chromodynamics. For invisible axions, cosmological and astrophysical observations impose the lower and upper limits on axion mass of µeV and meV respectively. The axion in such a mass range could be a promising candidate for the cold dark matter. The CAPP-8TB experiment searches for the axion by detecting photons, produced by the axion-photon coupling, resonating in a microwave cavity. The experiment has recently obtained a result of axion search in the mass range of 6.62-6.82 µeV. At the 90 % confidence level we probed the QCD axion down to a theoretical boundary, which is the most sensitive experimental result in the specific mass range to date. In this paper we will explain the detail of the experimental setup, parameters and analysis procedure. A plan for the next phase of the experiment for different mass ranges will also be discussed. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).