Search for Ultra-low Mass Dark Matter

International audience; The absence of observation of dark matter candidates above the GeV scale, at the LHC and in dedicated WIMP search experiments, led physicists to explore other mass domains, in particular below the electron-volt. Beside, the so-called strong CP problem is still an issue in the standard model. It can be solved by adding a new scalar field called axion. This scalar field could be a dark matter candidate. Depending of its coupling and in the range of mass ≈ [10^{−22},1] eV, it may solve the two issues described above at once. After the description of the strong CP problem and its simplest solution, I briefly present some mass limits for axions and similar fields (Axion Like Particle, Hidden Photon) and some of the experiments from which these limits have been extracted. At the end of this document, new limits on Hidden Photon are presented with a new experiment: Shuket.