Natural Alignment of Quark Flavors and Radiatively Induced Quark Mixings

Understand

The standard model does not provide an explanation of the observed alignment of quark flavors i.e.

• why are the up and down quarks approximately aligned in their weak interactions according to their masses? We suggest a resolution of this puzzle using a combination of left-right and Peccei-Quinn (PQ) symmetry.
• The quark mixings in this model vanish at the tree level and arise out of one loop radiative corrections which explains their smallness.
• The lepton mixings on the other hand appear at the tree level and are therefore larger.