Flavour puzzle or Why neutrinos are different?
  We present a short review of a 6-dimensional model where a flavour puzzle of the Standard Model fermions finds an elegant solution. The mechanism is based on an idea that the three fermionic generations originate from a single 6D family. The model explains in a natural way both charged fermions mass hierarchy and small mixings in the quark sector, and tiny neutrino masses and large neutrino mixings. We also discuss some phenomenological aspects of the model which can distinguish this class of the models from another one and can help to look for manifestations of new physics at colliders and other experiments. 
M. Libanov and F.-S. Ling
hep-ph