LABORATORI NAZIONALI DI FRASCATI Speaker: Michele Redi (CERN)
One of the main problems of axion scenarios is to explain the origin of an almost exact Peccei-Quinn symmetry only broken by the QCD anomaly.
In this talk I will present several models where the QCD axion arises accidentally. This can be realised in confining gauge theories where the Peccei-Quinn symmetry can emerge accidentally if the representations are chiral. In some cases these models can be understood as the deconstruction of 5-dimensional gauge theories but more general constructions are possible. Phenomenological features will be discussed.