Related papers: Clearing up the Strong $CP$ problem
We revisit the supersymmetric CP problem and find that it can be naturally resolved if the origin of CP violation is closely related to the origin of flavour structures. In this case, the supersymmetry breaking dynamics do not bring in any…
On general grounds based on quantum field theory the decay amplitude for $\Sigma^0 \to \Lambda \gamma$ consists of a parity conserving magnetic and a parity violating electric dipole transition moment. Because of the subsequent…
An unexpected explanation for neutrino mass, Dark Matter (DM) and Dark Energy (DE) from genuine Quantum Chromodynamics (QCD) of the Standard Model (SM) is proposed here, while the strong CP problem is resolved without any need to account…
We suggest a solution to the strong CP problem in which there are no axions involved. The superselection rule of the \theta-vacua is dynamically lifted in such a way that an infinite number of vacua are accumulated within the…
Models which solve the strong CP problem by employing discrete spacetime symmetries generically suffer fine-tuning and quality problems. We demonstrate that these issues are greatly ameliorated when the only source of spontaneous CP…
CP invariance is a very attractive solution to the strong CP problem in QCD. This solution requires the vanishing ${\rm arg}\,[{\rm det}\, M_d\, {\rm det} M_u]$, where the $M_d$ and $M_u$ are the mass matrices for the down- and up-type…
We propose an alternative to the axion mechanism for addressing the charge parity (CP) problem in quantum chromodynamics (QCD). Our approach involves imposing CP as an inherent symmetry of the Lagrangian, which is then spontaneously broken.…
Imposing CP or P forces the QCD topological angle to be either $\bar\theta=0$ or $\bar\theta=\pi$. However, only the former is phenomenologically viable. This implies that the assumption of CP or P alone cannot provide a framework for…
A permanent electric dipole moment (EDM) of a particle or system is a separation of charge along its angular-momentum axis and is a direct signal of T-violation and, assuming CPT symmetry, CP violation. For over sixty years EDMs have been…
A spontaneously-broken CP provides an alternative to the KM mechanism for CP violation with the advantage that the strong CP problem is solved. We consider, for such a model with a new gauged U(1), the incorporation of low-energy…
We propose a new solution to the strong-CP problem. It involves the existence of an unbroken gauged $U(1)_X$ symmetry whose gauge boson gets a Stuckelberg mass term by combining with a pseudoscalar field $\eta (x)$. The latter has…
Motivated by recent claims questioning the existence of strong CP violation, we present a pedagogical review of CP violation in Quantum Chromodynamics (QCD). Using fundamental properties of the QCD partition function, we analyze the…
The conservation of $CP$ in QCD has been shown to follow from a careful treatment of the path integral and canonical quantization in arXiv:2001.07152 and arXiv:2403.00747. Here, we refute the critique of these results put forth in…
Using QCD sum rules, we calculate the electric dipole moment of the neutron d_n induced by all CP violating operators up to dimension five. We find that the chromoelectric dipole moments of quarks \tilde d_i, including that of the strange…
Electric dipole moments (EDMs) of nucleons and nuclei, which are sought as evidence of CP violation, require lattice calculations to connect constraints from experiments to limits on the strong CP violation within QCD or CP violation…
Lattice QCD is rapidly progressing toward being able to reliably compute the electric dipole moment of the neutron as a function of the strong CP-violating parameter theta. Present day calculations are performed at unphysical values of the…
The storage ring proton electric dipole moment (pEDM) experiment is the first direct search for a proton EDM. It will improve on the current (indirect) limit by at least four orders of magnitude and surpass the current sensitivity (set by…
We present a solution to the strong CP problem, which relies on the horizontal gauge symmetry and CP invariance in a full theory. Similar to other Nelson-Barr type solutions, CP violation in both the strong and weak sectors in the Standard…
A nonvanishing value for the electric dipole moment (EDM) of the neutron is a prominent signature for CP violation. The EDM induced by the Kobayashi-Maskawa mechanism of the standard model (SM) has a small magnitude and its detection will…
The QCD axion is one of the most compelling solutions of the strong CP problem. There are major current efforts into searching for an ultralight, invisible axion, which is believed to be the only phenomenologically viable realization of the…