https://doi.org/10.1140/epjc/s10052-018-5883-0
Regular Article - Theoretical Physics
A minimal scale invariant axion solution to the strong CP-problem
1
Institute for Nuclear Research of Russian Academy of Sciences, Moscow, 117312, Russia
2
Ecole Polytechnique Federale de Lausanne, 1015, Lausanne, Switzerland
* e-mail: tokareva@ms2.inr.ac.ru
Received:
29
January
2018
Accepted:
10
May
2018
Published online:
28
May
2018
We 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. We add the minimal number of new particles and 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. We present a set of general conditions which makes this scenario viable and an explicit example of an effective theory possessing spontaneous breaking of scale invariance. We show that this description works both for inflation and low-energy physics in the electroweak vacuum. This scenario can provide a self-consistent inflationary stage and, at the same time, successfully avoid the cosmological bounds on the axion. Our general predictions are the existence of colored TeV mass fermion and the QCD axion. The latter has all the properties of the KSVZ axion but does not contribute to dark matter. This axion can be searched via its mixing to a photon in an external magnetic field.
© The Author(s), 2018
