The axion came into play in the late seventies in an attempt to solve the strong CP problem, i.e. the absence of CP violation in the strong interaction. It is a pseudoscalar boson whose mass and couplings to standard model particles are inversely proportional to /f/A,  an energy scale related to the spontaneous breaking of a newly introduced simmetry (the so called Peccei and Quinn simmetry).
Several axion models have been proposed, with the common feature of low mass and very weak interactions, making this particle an excellent Dark Matter candidate.
Axions, and the related Axion Like Particles (ALPs), have been searched for in laboratory experiments since their proposal: a variety of uncommon techniques have been employed and new ones are also appearing in the literature.
The QUAX project includes an R&D activity aimed at demonstrating the feasibility of a dark matter axion detector (haloscope) exploiting the axion electron coupling. To this end, a ferrimagnetic material is coupled to a microwave resonant cavity and a sensitive detector looks for excess power released into the system by an axion wind. After pioneering results on novel types of resonant cavities working inside strong magnetic fields, we are now also building an haloscope that will exploits the axion photon coupling.  In this talk, after a short introduction on axion physics, I will present the latest results obtained by the QUAX collaboration, i.e. improved limits on the dark matter axion-electron and axion-photon couplings for an axion mass around 43 microeV.

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