We report the results of an axion dark matter search over an axion mass range of 9.39-9.51 μeV. A flux-driven Josephson parametric amplifier (JPA) was added to the cryogenic receiver chain. A system noise temperature of as low as 200 mK was achieved, which is the lowest recorded noise among published axion cavity experiments with phase-insensitive JPA operation. In addition, we developed a two-stage scanning method which boosted the scan speed by 26%. As a result, a range of two-photon coupling in a plausible model for the QCD axion was excluded with an order of magnitude higher in sensitivity than existing limits.
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http://dx.doi.org/10.1103/PhysRevLett.130.091602 | DOI Listing |
Phys Rev Lett
December 2024
Departament de Física Aplicada, Universitat d'Alacant, 03690 Alicante, Spain.
The existence of light QCD axions, whose mass depends on an additional free parameter, can lead to a new ground state of matter, where the sourced axion field reduces the nucleon effective mass. The presence of the axion field has structural consequences, in particular, it results in a thinner (or even prevents its existence) heat-blanketing envelope, significantly altering the cooling patterns of neutron stars. We exploit the anomalous cooling behavior to constrain previously uncharted regions of the axion parameter space by comparing model predictions with existing data from isolated neutron stars.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Department of Physics, Kyungpook National University, Daegu 41566, Republic of Korea.
We give for the first time theoretical estimates of unknown rare electron-capture (EC) decay branchings of ^{44}Ti, ^{57}Co, and ^{139}Ce, relevant for searches of (exotic) dark-matter particles. The nuclear-structure calculations have been done exploiting the nuclear shell model with well-established Hamiltonians and an advanced theory of β decay. In the absence of experimental measurements of these rare branches, these estimates are of utmost importance for terrestrial searches of dark-matter particles, such as axionic dark matter in the form of axionlike particles, anapole dark matter, and dark photons in nuclear transitions.
View Article and Find Full Text PDFPhys Rev Lett
November 2024
Physics Department, University of Patras, Patras, Greece.
Hypothetical axions provide a compelling explanation for dark matter and could be emitted from the hot solar interior. The CERN Axion Solar Telescope has been searching for solar axions via their back conversion to x-ray photons in a 9-T 10-m long magnet directed toward the Sun. We report on an extended run with the International Axion Observatory pathfinder detector, doubling the previous exposure time.
View Article and Find Full Text PDFPhys Rev Lett
November 2024
Department of Physics, KAIST, Daejeon 34141, Republic of Korea.
Eur Phys J C Part Fields
November 2024
ETH Zürich, Institute for Particle Physics and Astrophysics, 8093 Zurich, Switzerland.
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