TH Cosmo Coffee

A minimal scale invariant axion solution to the strong CP-problem

by Anna Tokareva (Institute for Nuclear Research of RAS, Moscow)

4-S-030 (CERN)



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I present a scale-invariant extension of the Standard model allowing for the Kim-Shifman-Vainstein-Zakharov (KSVZ) axion solution of the strong CP problem in QCD. I show that the Peccei-Quinn scalar might be identified with the complex dilaton field. Scale invariance, together with the Peccei-Quinn symmetry, is broken spontaneously near the Planck scale before inflation, which is driven by the Standard Model Higgs field. Under the set of general conditions, this scenario can be viable. I provide an explicit example of an effective theory possessing spontaneous breaking of scale invariance. This description works both for inflation and low-energy physics in the electroweak vacuum. The scenario can provide a self-consistent inflationary stage and, at the same time, successfully avoid the cosmological bounds on the axion. The general predictions are the existence of coloured TeV mass fermion and the QCD axion. The latter has all the properties of the KSVZ axion but does not contribute to dark matter. However, this axion can be searched via it's mixing to a photon in an external magnetic field.

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