Grand Color axion

• Published in: The journal of high energy physics Vol. 2022; no. 10; pp. 25 - 26
• Main Authors: Valenti, Alessandro, Vecchi, Luca, Xu, Ling-Xiao
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 05.10.2022; Springer Nature B.V; SpringerOpen
• Subjects: Astronomical models; Axions and ALPs; Classical and Quantum Gravitation; Color; Confining; Cosmology; Couplings; CP violation; Decay rate; Elementary Particles; Fermions; Gauge invariance; High energy physics; New Gauge Interactions; Phenomenology; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; Standard model (particle physics); String Theory; Topology; Axions and ALPs; New Gauge Interactions
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP10(2022)025

A bstract We present a model that solves the strong CP problem via an axion parametrically heavier than the standard one. Within this picture the Standard Model quarks are embedded into a larger non-abelian Grand Color group that at high scales splits into ordinary QCD and an additional confining dynamics under which exotic chiral fermions are charged. Crucially, the vacuum expectation value of the axion is automatically relaxed to zero because the only renormalizable source of explicit CP violation, beyond those encoded in the topological angles, is contained in the Standard Model Yukawa couplings, and is therefore very suppressed. The Grand Color axion potential is controlled by the scale of the new confining group and is much larger than the QCD contribution, such that its dynamics is less exposed to the so-called “axion quality problem”. Potentially observable corrections to the effective topological angle can also arise, in our model as well as in a large class of heavy axion scenarios, from non-renormalizable Peccei-Quinn- conserving interactions, which introduce a new “heavy axion quality problem”. Our model has a very minimal field content, it relies entirely on gauge invariance and does not require the introduction of additional symmetries beyond the usual one postulated by Peccei and Quinn. The phenomenology is very rich and can be tested at colliders as well as via cosmological observations. A particularly interesting portion of parameter space predicts a visible Grand Color axion of mass above the GeV and decay constant larger than a few TeV.