Isospin-Violating Meson-Nucleon Vertices as an Alternate Mechanism of Charge-Symmetry Breaking

Abstract

We compute isospin-violating meson-nucleon coupling constants and their consequent charge-symmetry-breaking nucleon-nucleon potentials. The couplings result from evaluating matrix elements of quark currents between nucleon states in a nonrelativistic constituent quark model; the isospin violations arise from the difference in the up and down constituent quark masses. We find, in particular, that isospin violation in the omega-meson--nucleon vertex dominates the class IV CSB potential obtained from these considerations. We evaluate the resulting spin-singlet--triplet mixing angles, the quantities germane to the difference of neutron and proton analyzing powers measured in elastic $\vec{n}-\vec{p}$ scattering, and find them commensurate to those computed originally using the on-shell value of the $\rho$-$\omega$ mixing amplitude. The use of the on-shell $\rho$-$\omega$ mixing amplitude at $q^2=0$ has been called into question; rather, the amplitude is zero in a wide class of models. Our model possesses no contribution from $\rho$-$\omega$ mixing at $q^2=0$, and we find that omega-meson exchange suffices to explain the measured $n-p$ analyzing power difference~at~183 MeV.

20 pages, revtex, 3 uuencoded PostScript figures

References in corpus (9)

• The Momentum Dependence of the $\rho -\omega$ Mixing Amplitude in a Hadronic Model
• Constraints on the momentum dependence of rho-omega mixing
• The Off Shell $\rho$-$\omega$ Mixing in the QCD Sum Rules
• Charge-Symmetry Breaking, Rho-Omega Mixing and the Quark Propagator
• Charge symmetry breaking via rho-omega mixing from model quark-gluon dynamics
• Off-shell Behavior of the $\pi -\eta$ Mixing Amplitude
• $q^2$-Dependence of Meson Mixing in Few-Body Charge Symmetry Breaking: ${\pi }^o-\eta$ Mixing to One Loop in Chiral Perturbation Theory
• Charge-Symmetry-Breaking Potentials from Isospin-Violating Meson-Baryon Coupling Constants
• Pi- Eta Mixing from QCD Sum Rules

Cited by in corpus (10)

• Rho-omega mixing, vector meson dominance and the pion form-factor
• Particle Physics Models for the 17 MeV Anomaly in Beryllium Nuclear Decays
• Isospin violation in the vector form factors of the nucleon
• The Nucleon-Mass Difference in Chiral Perturbation Theory and Nuclear Forces
• Anomalies in ${}^8$Be nuclear transitions and $(g-2{)}_{e,\mu }$: towards a minimal combined explanation
• Matter induced rho-omega mixing
• Isospin Breaking in the Pion-Nucleon Coupling from QCD Sum Rules
• QCD Sum Rules: Isospin Symmetry Breakings in Pion-Nucleon Couplings
• Meson mixing amplitudes in asymmetric nuclear matter
• The Okamoto-Nolen-Schiffer anomaly without rho-omega mixing