A grand unification of flavour with testable predictions

Abstract

We present a grand unification of flavour based on the group O (14) = SO(14) ⊗ K'. The novel feature of this model is that the discrete symmetry K' is not the internal parity. This implies a fermion assignment different from the usual O(14) with important consequences on the low energy phenomenology. One new fermion family with V - A weak interactions and four new families with V + A character are predicted, with masses less than 250 GeV. The cosmological bound on light neutrino species forces us to keep an SU(2) family group acting on the V + A families unbroken until low energy. Depending on the hierarchy pattern, either we recover the standard model predictions or a new scenario emerges with substantial departures in the neutral current phenomenology.