Flavor Hierarchies from Clockwork in SO(10) GUT

TL;DR

This paper integrates the clockwork mechanism into $SO(10)$ GUTs to naturally generate fermion mass hierarchies with order-one Yukawa couplings, without requiring generation-specific symmetries, and explores both SUSY and non-SUSY frameworks.

Contribution

It introduces a minimal Yukawa sector extended with clockwork chains in $SO(10)$ GUTs, providing a novel approach to fermion mass hierarchies without special symmetries.

Findings

Hierarchical fermion masses achieved with order-one Yukawa couplings.

Clockwork extension works in both SUSY and non-SUSY $SO(10)$ models.

In non-SUSY case, solves strong CP problem and offers axion dark matter.

Abstract

The clockwork mechanism, which can naturally explain the origin of small numbers, is implemented in $SO(10)$ grand unified theories to address the origin of hierarchies in fermion masses and mixings. We show that a minimal Yukawa sector involving a $10_H$ and $\overline{126}_H$ of Higgs bosons, extended with two clockwork chains consisting of $16+\overline{16}$ vector-like 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 $SO(10)$ 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 non-trivial charges, which solves the strong CP problem and provides axion as a dark matter candidate.