Related papers: Do Minimal Parity Solutions to the Strong CP Probl…
Quantum Chromodynamics (QCD) admits a topological $\bar{\theta}$ term that violates charge-parity ($CP$) symmetry, yet experiments indicate that $\bar{\theta}$ is extremely small. To investigate this problem in a controlled setting, we…
We show that a recently proposed solution to the Hierarchy Problem simultaneously solves the Strong CP Problem, without requiring an axion or any further new physics. Consistency of black hole physics implies a non-trivial relation between…
We discuss a class of models in which CP is violated softly in a heavy sector adjoined to the standard model. Heavy-sector loops produce the observed CP violation in kaon physics, yielding a tiny and probably undetectable value for…
We analyze the minimal supersymmetric left-right model with non-re\-nor\-malizable interactions induced by higher scale physics and study its {\it CP} violating properties. We show that it: (i) solves the strong {\it CP} problem; (ii)…
A non-axion solution to the Strong CP Problem is proposed that works even in the context of gravity-mediated supersymmetry breaking. Both $\epsilon'/\epsilon$ and indirect CP violation in the $B-\bar{B}$ are predicted to be unobservably…
The strong CP problem can be solved in Parity symmetric theories with electroweak gauge group containing $SU(2)_L \times SU(2)_R$ broken by the minimal Higgs content. Neutrino masses may be explained by adding the same number of gauge…
We study the possibility of soft breaking effects of the generalized parity within the minimal Left-Right model. One aim of the paper is to elaborate on the potentiality, the limit, and the predictivity of a restored parity at high scale.…
One possible solution to the strong CP problem is that CP is an exact symmetry, spontaneously broken at some scale. Some years ago, Nelson and Barr suggested a mechanism for obtaining $\theta=0$ at tree level in this framework, and showed…
The QCD Lagrangian contains a CP violating gluon density term with a physical coefficient $\bar{\theta}$. The upper bound on the electric dipole moment of neutron implies that the value of $\bar{\theta}$ should be extremely small rather…
Recent studies have claimed that the strong $CP$ problem does not occur in QCD, proposing a new order of limits in volume and topological sectors when studying observables on the lattice. In order to shed light on this issue, we study the…
Solutions of the Strong CP Problem based on the spontaneous breaking of CP must feature a non-generic structure and simultaneously explain a coincidence between a priori unrelated CP-even and CP-odd mass scales. We show that these…
On the basis of allowed local gauge symmetries, the QCD Lagrangian admits a CP-violating term proportional to the topological charge density, commonly referred to as the $\theta$ term. A priori, any value of $\theta$ is consistent with the…
We find a solution to the Strong CP problem that may be testable at the LHC and future colliders. In this solution CP is broken by parity conserving terms, while parity breaking VEVs conserve CP. The quark mass matrix is Hermitian at the…
We propose a model that provides a simultaneous solution to the doublet-triplet splitting problem of grand unified theories, the electroweak hierarchy problem and the strong CP problem. The mechanism is based on the dynamics of two…
We revisit the minimal Nelson-Barr model for solving the strong CP problem through the idea of spontaneous CP breaking. The minimal model suffers from the quality problem, which means that the strong CP angle is generated by…
It is shown that the quark mass aligns QCD $\theta$ vacuum in such a way that the strong CP is conserved, resolving the strong CP problem.
The strong CP problem is one of many puzzles in the theoretical description of elementary particle physics that still lacks an explanation. While top-down solutions to that problem usually comprise new symmetries or fields or both, we want…
We propose a novel solution to the Strong CP problem -- to explain why SU(3) strong force has a nearly zero theta angle $\bar\theta_3 \simeq 0$ for the 4d Standard Model (SM). The new ingredient is Symmetric Mass Generation (SMG):…
We study spontaneous CP violation as a solution to the strong CP problem in left-right symmetric theories. The discrete CP symmetry is broken by a complex vacuum expectation value of a right-handed Higgs doublet. Heavy vectorlike down-type…
I put forward an SU(2)_L x SU(2)_R x U(1) model in which spontaneously broken parity symmetry makes it that strong CP violation only arises at three-loop level. All leptons and up-type quarks are in doublets either of SU(2)_L or of SU(2)_R,…