Four decades after its prediction, the axion remains the most compelling solution to the strong CP problem and a well motivated dark matter candidate, inspiring several ultrasensitive experiments based on axion-photon mixing. The experimental landscape for axion searches is evolving extremely fast: consolidated detection techniques are now facing next-generation experiments with ambitious sensitivity goals, while novel and ingenious detection concepts promise to open for exploration new ranges of parameter space previously considered unreachable. AXIONRUSH deals with an ambitious program to reshape the parameter space of the QCD axion by developing new model building directions and by revisiting from an ultraviolet perspective axion couplings to photons, nucleons, electrons, including also flavour and CP violating ones. The main goal of AXIONRUSH is to bridge theoretical aspects of axion physics with experiments and to provide a global comparison of general axion models with experimental sensitivities and astrophysical bounds. The development of these new theoretical tools will enlarge the physics scopes of the axion experimental program at DESY, Hamburg, by further addressing specific research goals related to the experiments ALPS-II, IAXO, MADMAX and Belle II. A complementary objective of AXIONRUSH is to investigate scenarios where the Peccei Quinn mechanism is embedded into grand unified theories. The latter provide a predictive framework for narrowing down the axion mass range, with a potential impact on the scanning strategy of the axion dark matter experiments CASPER-Electric and ABRACADABRA. A major intention of this latter objective is the construction of a minimal, unified scenario aiming at a self-contained description of particle physics, from the electroweak scale to the Planck scale, and cosmology, from inflation until today.
[Picture from L. Di Luzio, M. Giannotti, E. Nardi, L. Visinelli, The landscape of QCD axion models]
Work funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Individual Fellowship AXIONRUSH (grant agreement No 840791)