Journal of High Energy Physics

, 2018:35 | Cite as

A flavorful factoring of the strong CP problem

  • Prateek AgrawalEmail author
  • Kiel Howe
Open Access
Regular Article - Theoretical Physics


Motivated by the intimate connection between the strong CP problem and the flavor structure of the Standard Model, we present a flavor model that revives and extends the classic mu = 0 solution to the strong CP problem. QCD is embedded into a SU(3)1 × SU(3)2 × SU(3)3 gauge group, with each generation of quarks charged under the respective SU(3). The non-zero value of the up-quark Yukawa coupling (along with the strange quark and bottom-quark Yukawas) is generated by contributions from small instantons at a new scale M ≫ ΛQCD. The Higgsing of SU(3)3 → SU(3)c allows dimension-5 operators that generate the Standard Model flavor structure and can be completed in a simple renormalizable theory. The smallness of the third generation mixing angles can naturally emerge in this picture, and is connected to the smallness of threshold corrections to \( \overline{\theta} \). Remarkably, \( \overline{\theta} \) is essentially fixed by the measured quark masses and mixings, and is estimated to be close to the current experimental bound and well within reach of the next generation of neutron and proton EDM experiments.


Anomalies in Field and String Theories Beyond Standard Model CP violation Solitons Monopoles and Instantons 


Open Access

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Copyright information

© The Author(s) 2018

Authors and Affiliations

  1. 1.Department of PhysicsHarvard UniversityCambridgeU.S.A.
  2. 2.Fermi National Accelerator LaboratoryBataviaU.S.A.

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