Supersizing axions with small size instantons

Abstract

We construct a new framework to calculate the enhancement of axion masses and concomitant effects on axion-meson mixing arising from small size instantons (SSIs), which originate in models featuring an extended color gauge symmetry. The framework is based on an explicit evaluation of 't Hooft determinantal operators that partition into instanton amplitudes, affording a more precise determination of the axion-diphoton coupling than previous results. Using an explicit model first presented in Ref.[1], we demonstrate that axions solving the strong CP problem can have electroweak scale masses and higher, driven by SSI effects. Such collider axions are prime targets for resonance searches at the Large Hadron Collider and afford a unique anchor for motivating extended color symmetries.

Enhancing Searches for Heavy QCD Axions via Dimuon Final States

“…The latter is the case if the axion mass is much larger than that dictated by the strong dynamics-as in the so-called heavy QCD axion models. The axion mass can be enhanced in ways that still preserve the CP symmetry [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. (See also [51][52][53] for early work on raising the axion mass.…”