A New Class of Solutions to the Strong CP Problem with a Small Two-Loop theta

Abstract

We present a new class of models which produce zero theta (QCD} angle at the tree and one-loop level due to hermiticity of sub-blocks in the extended quark mass matrices. The structure can be maintained typically by non-abelian generation symmetry. Two examples are given for this class of solutions.

Comments: 4 pages, 2 figures