Results on axion physics from the CAST Experiment at CERN

TL;DR

The CERN Axion Solar Telescope (CAST) has set new experimental limits on axion-photon coupling, surpassing previous bounds and exploring a broader axion mass range, thereby advancing the search for axions predicted by theoretical models.

Contribution

This work provides the first laboratory limits on axion-photon coupling below 10^{-10} GeV^{-1} for axion masses under 0.02 eV, and extends the mass range up to 1.1 eV.

Findings

Set new upper limits on axion-photon coupling g_{aγ} below 10^{-10} GeV^{-1} for m_a < 0.02 eV.

Surpassed astrophysical bounds for axion-photon coupling.

Extended the axion mass search range up to 1.1 eV.

Abstract

Axions are expected to be produced in the sun via the Primakoff process. They may be detected through the inverse process in the laboratory, under the influence of a strong magnetic field, giving rise to X-rays of energies in the range of a few keV. Such an Axion detector is the CERN Axion Solar Telescope (CAST), collecting data since 2003. Results have been published, pushing the axion-photon coupling g$_{a\gamma}$ below the 10$^{-10}$ GeV$^{-1}$ limit at 95% CL, for axion masses less than 0.02 eV. This limit is nearly an order of magnitude lower than previous experimental limits and surpassed for the first time limits set from astrophysical arguments based on the energy-loss concept. The experiment is currently exploring axion masses in the range of 0.02 eV $< m_a <$ 1.1 eV. In the next run, currently under preparation, the axion mass explored will be extended up to the limit of 1.1 eV, testing for the first time the region of theoretical axion models with the axion helioscope method.