The weak parity-violating pion nucleon coupling: Why its weaker that weak

Journal Article · Sun Oct 01 04:00:00 EDT 1995 · Bulletin of the American Physical Society

OSTI ID:255567

Kisslinger, L S ^[1]

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1. Carnegie Mellon Univ., Pittsburgh, PA (United States)

Using the methods of QCD sum rules for a nucleon in an external pion field we investigate the weak parity-violating pion-nucleon coupling. We are able to use standard electroweak theory and include both perturbative and nonperturbative QCD effects. We find for the lowest-dimensional weak process a parity-violating pi-N coupling similar to the {open_quotes}best{close_quotes} values of quark models. There is, however, a large nonperturbative QCD effect caused by a vacuum susceptibility, a polarization of the quark condensate induced by the pion field. Determining the value of this susceptibility by a fit to the strong coupling constant, we find that withi our accuracy it almost completely cancels the quark-model type process. With our best value we predict that the pi-N parity-violating interaction is too small to be extracted by experiment. These vacuum susceptibilities, related to an early-universe phase transition, are important for future studies of hadronic properties in nuclear matter.

• OSTI ID: 255567
• Report Number(s): CONF-9510116--
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 10 Vol. 40; ISSN BAPSA6; ISSN 0003-0503
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
NUCLEAR MATTER
P INVARIANCE
PION-NUCLEON INTERACTIONS
QUANTUM CHROMODYNAMICS
QUARK MODEL
SYMMETRY BREAKING