Heavy Axion Research Articles

Strong CP and SUZ2

Solutions to the strong CP problem typically introduce new scales associated with the spontaneous breaking of symmetries. Absent any anthropic argument for small $\bar\theta$, these scales require stabilization against ultraviolet corrections. Supersymmetry offers a tempting stabilization mechanism, since it can solve the "big" electroweak hierarchy problem at the same time. One family of solutions to strong CP, including generalized parity models, heavy axion models, and heavy $\eta^\prime$ models, introduces $\mathbb{Z}_2$ copies of (part of) the Standard Model and an associated scale of $\mathbb{Z}_2$-breaking. We review why, without additional structure such as supersymmetry, the $\mathbb{Z}_2$-breaking scale is unacceptably tuned. We then study "SUZ$_2$" models, supersymmetric theories with $\mathbb{Z}_2$ copies of the MSSM. We find that the addition of SUSY typically destroys the $\mathbb{Z}_2$ protection of $\bar\theta=0$, even at tree level, once SUSY and $\mathbb{Z}_2$ are broken. In theories like supersymmetric completions of the twin Higgs, where $\mathbb{Z}_2$ addresses the little hierarchy problem but not strong CP, two axions can be used to relax $\bar\theta$.

Grand unification and heavy axion

We argue that sufficiently complex grand unified theories involving extra strong intractions that confine at very short distances may lead to a heavy axion solution of the CP problem of QCD. This axion may have a mass within the accessible energy range, and its low-energy interactions emerge through mixing with axial Higgs boson(s). Another signature of this scenario is softly broken Peccei-Quinn symmetry in the electroweak Higgs sector. We present a toy GUT exhibiting these features.

THE η6 AT LEP AND TRISTAN

The η6 is a “heavy axion” remnant of dynamical electroweak symmetry breaking by a color sextet quark condensate. Electroweak scale color instanton interactions allow it to be both very massive and yet be responsible for Strong CP conservation in the color triplet quark sector. It may have been seen at LEP via its two-photon decay mode and at TRISTAN via its hadronic decay modes.

HEAVY AXION ON SARK BRIDGE BETWEEN HIGGS AND TECHNICOLOR MODELS

It is shown how imposition of Peccei–Quinn symmetry leads to a heavy axion and strong constraints in the sark model. The axion and sark masses are derived. Analysis of chiral symmetry breaking leads to mass formulae for pseudo-Goldstone bosons; the lightest is between 44 and 125 GeV. A general picture which bridges between the sark model and a technicolor model, in terms of a new angle, is proposed.

Limits on heavy axion production from the reactionn(p, a)d

A search has been made for the creation of short-lived axions in the isovector transitionn(p, a)d decaying intoe+e−-pairs. The production of Peccei-Quinn axions can be excluded for 1.21<ma<1.98 MeVc−2 (90%CL). Limits on variant axion models are derived.

Strong QCD at high energies and a heavy axion

A new contribution to the axion mass occurs when QCD grows strong again at energies above the weak interaction mass scale. This contribution can naturally be significant when the Peccei-Quinn symmetry is spontaneously broken at similar energies. The effect is discussed with and without elementary scalar fields.

Raising the axion mass

We present a mechanism which raises the axion mass while maintaining the standard axion-fermion coupling and the removal of strong CP violation. The source of this new contribution to the axion mass is small color SU(3) instantins; these may be important if new physics above the weak interaction scale causes the color coupling constant to grow strong and produces anomalous dimensions for certain many-fermion operators. Strongly interacting hyperquarks may be responsible for both effects. We discuss the working of this mechanism in an explicit hypercolor-sideways interaction model in which a Peccei-Quinn symmetry appears naturally. In this particular model, heavy axion exchange could produce significant DODO mixing.

Superstrong Force with a Heavy Axion

A new, superstrong force (analogous to, but much stronger than, quantum chromodynamics) is introduced to the Peccei-Quinn extension of the standard model of weak and electromagnetic interactions. Strong CP nonconservation is naturally suppressed and the resulting heavy axion is compatible with the present experimental bounds. The strength of this new force and some of its properties are discussed.

A solution of the strong CP problem in models with scalars

We point out a possible solution to the strong CP problem within the context of a Weinberg-Salam model with two Higgs fields coupled in a Peccei-Quinn symmetric fashion. This is done by extending the colour group to a bigger simple group which is broken at some very high energy. The model contains a heavy axion. No old or new U(1) problem re-emerges.

Gauge Chiral U (1) Symmetry andCPInvariance in the Presence of Instantons

I explore a model which conserves $\mathrm{CP}$ automatically by the Peccei-Quinn mechanism and contains a relatively heavy axion consistent with the present data. Phenomenological implications are discussed.