Isospin-violating meson-nucleon vertices as an alternate mechanism of charge-symmetry breaking

Journal Article · Fri Mar 01 04:00:00 EST 1996 · Physical Review, C

DOI:https://doi.org/10.1103/PhysRevC.53.1143· OSTI ID:283407

Gardner, S ^[1]; Horowitz, C J ^[2]; Piekarewicz, J ^[3]

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1. Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States)
2. Nuclear Theory Center and Department of Physics, Indiana University, Bloomington, Indiana 47505 (United States)
3. Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306 (United States)

We compute isospin-violating meson-nucleon coupling constants and their consequent charge-symmetry-breaking (CSB) 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{endash}nucleon vertex dominates the class IV CSB potential obtained from these considerations. We evaluate the resulting spin-singlet{endash}triplet mixing angles, the quantities germane to the difference of neutron and proton analyzing powers measured in elastic {ital n}{searrow}-{ital p}{searrow} 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 {ital q}{sup 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 {ital q}{sup 2}=0, and we find that omega-meson exchange suffices to explain the measured {ital n}-{ital p} analyzing power difference at 183 MeV. {copyright} {ital 1996 The American Physical Society.}

• Research Organization: Indiana University
• DOE Contract Number: FG02-87ER40365; FG05-85ER25000; FG05-92ER40750
• OSTI ID: 283407
• Journal Information: Physical Review, C, Journal Name: Physical Review, C Journal Issue: 3 Vol. 53; ISSN PRVCAN; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
COUPLING
ISOSPIN
MASS
MATRIX ELEMENTS
MESON-NUCLEON INTERACTIONS
NUCLEON-NUCLEON POTENTIAL
OMEGA PARTICLES
POLARIZATION-ASYMMETRY RATIO
QUARK MODEL
QUARKS
SYMMETRY BREAKING
VERTEX FUNCTIONS
VIOLATIONS