Indirect signs of the Peccei-Quinn mechanism

Jordy De Vries, Patrick Draper, Kaori Fuyuto, Jonathan Kozaczuk, Dave Sutherland

Research output: Contribution to journalArticlepeer-review


In the standard model, the renormalization of the QCD vacuum angle θ is extremely tiny, and small θ is technically natural. In the general standard model effective field theory (SMEFT), however, Δθ is quadratically divergent, reflecting the fact that new sources of hadronic CP-violation typically produce O(1) threshold corrections to θ. The observation of such CP-violating interactions would therefore be in tension with solutions to the strong CP problem in which θ=0 is an ultraviolet boundary condition, pointing to the Peccei-Quinn mechanism as the explanation for why θ is small in the infrared. We study the quadratic divergences in θ arising from dimension-6 SMEFT operators and discuss the discovery prospects for these operators at electric dipole moment experiments, the LHC, and future proton-proton colliders.

Original languageEnglish (US)
Article number015042
JournalPhysical Review D
Issue number1
StatePublished - Jan 1 2019

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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