Flavor hierarchies from clockwork in SO(10) GUT

摘要

The clockwork mechanism, which can naturally explain the origin of small numbers, is implemented in S O ( 10 ) grand unified theories to address the origin of hierarchies in fermion masses and mixings. We show that a minimal Yukawa sector involving a 1 0 H and 126 ˉ H of Higgs bosons, extended with two clockwork chains consisting of 16 + 16 ˉ vectorlike fermions, can explain the hierarchical patterns with all the Yukawa couplings being of order one. Emergence of a realistic mass spectrum does not require any symmetry that distinguishes the three generations. We develop clockwork-extended S O ( 10 ) GUTs both in the context of SUSY and non-SUSY frameworks. Implementation of the mechanism in non-SUSY scenario assumes a Peccei-Quinn symmetry realized at an intermediate scale, with the clockwork sector carrying nontrivial charges, which solves the strong C P problem and provides axion as a dark matter candidate.