Strong CP Violation and large-N_c spin-flavor symmetry

2025/09/03 by Richardson, Thomas R.
#FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph) #Nuclear Theory (nucl-th)

paper · doi:10.48550/arxiv.2509.03613

Abstract

We revisit the contribution of the QCD θ term to the CP violating pion-nucleon couplings and the nucleon electric dipole moment in a combined large-N_c and chiral perturbation theory framework. In particular, we approach this issue through the emergent spin-flavor symmetry of the baryon sector at large but finite N_c. We obtain good agreement with previous analyses for the pion-nucleon couplings and show that the large-N_c framework indicates that tree-level contributions to the electric dipole moment possibly play a dominant role. The spin-flavor symmetry also enables us to provide novel constraints on CP violating pion-Δ couplings as well as the Δ electric dipole moment and ΔN transition moment.

Citations

• Towards the determination of CP-odd pion-nucleon couplings
• Chiral properties of the nucleon interpolating current and θ-dependent observables
• Nucleon Electric Dipole Moment from the θ Term with Lattice Chiral Fermions
• Review of lattice results concerning low-energy particle physics
• Electroweak baryogenesis and standard modelCPviolation
• STANDARD MODEL CP-VIOLATION AND BARYON ASYMMETRY
• A planar diagram theory for strong interactions
• Axial-Vector Vertex in Spinor Electrodynamics

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• Pion-Nucleon Scattering in Baryon Chiral Perturbation Theory combined with the 1/N_c Expansion
• Leading vector coupling in baryon semileptonic decays in large-N_c chiral perturbation theory revisited: Extension to decuplet baryons