Related papers: Axion Protection from Flavor
Quantum gravity introduces a new source of the combined parity (CP) violation in gauge theories. We argue that this new CP violation gets bundled with the strong CP violation through the coloured gravitational instantons. Consequently, the…
We study a class of supersymmetric models where the strong CP problem is solved through spontaneous CP violation, carried out by a complex scalar field that determines the Yukawa couplings of the theory. Assuming that one real component of…
Setting aside anthropic arguments, there is no reason for CP symmetry to be obeyed within the theory of quantum chromodynamics. However, no such violation of CP symmetry has ever been observed in a strongly interacting experiment. This is…
Discrete flavor symmetry is often introduced for explaining quark/lepton masses and mixings. However, its spontaneous breaking leads to the appearance of domain walls, which is problematic for cosmology. We consider a possibility that the…
We study a 2N-flavor effective theory of N-flavor QCD. With the axial anomaly accounted for in the effective theory by a 't Hooft interaction, only QCD conserved currents survive. However, there is a residual discrete symmetry with…
We study QCD axion or cosmological axion-like particles (ALPs) in a model inspired by the recent interest in 4-dimensional clockwork models, with the global symmetry being accidentally enforced by a gauge abelian quiver with scalar…
The axion solution of the strong CP problem is reviewed together with the other strong CP solutions. We also point out the quintessential axion(quintaxion) whose potential can be extremely flat due to the tiny ratio of the hidden sector…
We construct a model of spontaneous CP violation in E6 supersymmetric grand unified theory. In the model, we employ an SU(2)F flavor symmetry and an anomalous U(1)A symmetry. The SU(2)F flavor symmetry is introduced to provide the origin of…
The physical origin of the strong CP problem in QCD, rooted in the structures of the vacuum of the standard model, is reviewed. The chiral solution to this problem, with its accompanying axion, is explained and various characteristics of…
Axion models with generation-dependent Peccei-Quinn charges can lead to flavor-changing neutral currents, thus motivating QCD axion searches at precision flavor experiments. We rigorously derive limits on the most general effective…
Supersymmetric models with a high supersymmetry breaking scale give, in general, large contributions to epsilon_K and/or to various electric dipole moments, even when contributions to CP conserving, flavor changing processes are…
Within the general framework of using spontaneous CP violation to solve the strong CP problem, we construct a variant Nelson-Barr model in which the Standard Model (SM) quark contribution to the strong CP phase is cancelled by new heavy…
The fundamental constraint on two Higgs doublet models comes from the requirement of sufficiently suppressing flavor-changing neutral currents. There are various standard approaches for dealing with this problem, but they all tend to share…
Common lore suggests that $N$-color QCD with massive quarks has no useful order parameters which can be non-trivial at zero baryon density. However, such order parameters do exist when there are $n_f$ quark flavors with a common mass and…
Three symmetry constraints on the CP violations in QCD are discussed in this paper. In order to generate CP violating observables from QCD, these constraints require: (1) spontaneous chiral symmetry breaking, (2) explicit chiral symmetry…
We highlight general issues associated with quality and naturalness problems in theories of light QCD-axions, axion-like particles, and relaxions. We show the presence of Planck-suppressed operators generically lead to scalar coupling of…
We argue that demanding a consistent cosmological history, including the absence of domain walls and strongly interacting relics at the Peccei-Quinn scale, singles out two concrete realizations of hadronic QCD axions as viable dark matter…
The Nelson-Barr (NB) mechanism to solve the strong CP problem assumes CP conservation, arranges vanishing $\bar{\theta}$ at tree-level and requires vector-like quarks (VLQs) to transmit the CP breaking to the SM. We analyze the flavor…
The axion is a hypothetical elementary particle postulated by the Peccei-Quinn theory to resolve the strong CP problem in QCD. If axions exist and have low mass, they are a candidate for dark matter as well. So far our knowledge of the…
Our knowledge of quark-flavor physics and CP violation increased tremendously over the past five years. It is confirmed that the Standard Model correctly describes the dominant parts of the observed CP-violating and flavor-changing…