The axion flavour connection

A bstract local flavour symmetry acting on the quarks of Standard Model can automatically give rise to an accidental global U(1) which remains preserved from sources explicit breaking up a large operator dimension, while it gets spontaneously broken together with symmetry. Such non-fundamental symmetries are often endowed mixed QCD anomaly, so that strong CP problem is solved via axion mechanism. We illustrate general features required realise this scenario, and we discuss simple construction based group SU(3) × SU(2) F how mass hierarchies arise ensuring at same time high quality Peccei-Quinn