Related papers: What can solve the Strong CP problem?
Parity and CP symmetries are broken in the world around us. Nonetheless, parity (or CP) may be a gauge symmetry which is higgsed in our universe. This is assumed in many scenarios for physics beyond the Standard Model, including the classic…
It is argued that in the context of supersymmetry, the Strong CP Problem is most naturally seen as an aspect (particularly severe) of the whole complex of flavor-violating and CP-violating problems of supersymmetry. It is shown that certain…
An analogous "Strong CP problem" is identified in a toy model in 2-dimensional spacetime: a general 1+1d abelian U(1) anomaly-free chiral fermion and chiral gauge theory with a generic theta instanton term $\frac{\theta}{2 \pi} \int F$. The…
Addressed is the question of whether a natural mechanism exists to resolve the strong CP problem. The analogous issue for the two-dimensional $CP^{N-1}$ models is analyzed using computer simulations.
We sketch recent progress and promising future directions for research connected with the strong CP problem. Topics surveyed include axion dark matter substructure and its gravitational detection; axion model building and the quality…
The origin of CP violation is a major mystery, especially in relation to the strong CP problem. CP being a spontaneously broken symmetry could provide an elegant solution. However, such models have difficulty making themselves compatible…
We use parity (P) to set $\theta_{QCD}$ to zero in the minimal left-right symmetric model with a bi-doublet Higgs, add a heavy vectorlike quark family, and obtain in a novel manner the Nelson Barr (NB) form associated so far only with…
The extra-dimensional axion solves the strong CP problem while largely circumventing the quality problem that plagues its four-dimensional counterparts. Such high quality can be clearly understood in terms of the generalized global…
Quantum Chromodynamics (QCD) is the theory of the strong interactions within the Standard Model of particle physics, which explains more than 99% of the mass of the visible Universe. However, there is evidence that a substantial portion of…
We investigate what it takes for the axion to address the strong CP problem in the presence of explicit Peccei-Quinn (PQ) symmetry breaking effects besides the strong interaction. In cases where the PQ-Higgsing scalar field directly couples…
In a world devoid of axions, the smallness of the strong CP phase can have implications for leptonic CP violation being probed by neutrino experiments. For example, if nature adopted an axionless solution to the strong CP problem, the same…
CP non-invariance is strongly limited by present experiments, while extra sources of CP-violation are needed for a successful baryogenesis. Motivated by those observations we consider a model which predicts spontaneous violation of CP at…
We show that a class of parity based solutions to the strong CP problem predicts new colored particles with mass at the TeV scale, due to constraints from Planck suppressed operators. The new particles are copies of the Standard Model…
In this work, we critically reanalyze the explicit breaking of the Peccei-Quinn global symmetry -- and the corresponding corrections to the QCD axion potential -- induced by gravity. Specifically, we examine the role of gravitational…
The axion solution to the strong CP problem calls for an explanation as to why the Lagrangian should be invariant under the global Peccei-Quinn symmetry, U(1)_PQ, to such a high degree of accuracy. In this paper, we point out that the…
Among solutions of the strong CP problem, the "invisible" axion in the narrow axion window is argued to be the remaining possibility among natural solutions on the smallness of $\bar{\theta}$. Related to the gravity spoil of global…
The non-perturbative solution to the strong CP problem with magnetic monopoles as originally proposed by the author is described. It is shown that the gauge orbit space with gauge potentials and gauge tranformations restricted on the space…
We show that there are many candidates for the quintessence and/or the QCD axions in a class of chiral $U(1)$ gauge theories. Their qualities are high enough to serve as the dark energy and/or to solve the strong CP problem. Interestingly,…
The strong CP problem was solved by Peccei & Quinn by introducing axions, a viable candidate for Dark Matter (DM). Here the PQ approach is modified so to yield also Dark Energy (DE). DM and DE arise, in fai proportions, from a single scalar…
We consider a class of baryogenesis models where the Lagrangian in the visible sector is Charge-Parity (CP) invariant and a baryon asymmetry is produced only when quantum statistics is taken into account. The CP symmetry is broken by matter…