Nearly massless pion in a modified bag model

Journal Article · Sun Apr 01 04:00:00 EST 1984 · Phys. Rev. D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.29.1455· OSTI ID:7000797

Ho-Kim, Q; Lee, H C

The properties of the pions are studied in a modified bag model. The pion wave function is approximated by the projection of the qq-bar wave function in the bag that has zero center-of-mass motion. The parameters of the model are determined by the usual stability condition and the additional requirement that the pion mass m/sub ..pi../ approach zero in a manner consistent with the hypothesis of partially conserved axial-vector current (PCAC). This fixes the bag volume energy to be m/sub ..pi..//4. Static pion properties are in good agreement with data provided that quarks in the pion are correlated by a modulating function characterized by a correlation momentum p/sub c/approx.300 MeV/c. The bag-model and Nambu-Goldstone views of the pion are reconciled as a distinction is made between constituent and current quarks. Assuming their fields to be related by a transformation analogous to that of Nambu and Jona-Lasinio we calculate the vacuum expectation value of the current quark density to be 0.04 GeV/sup 3/, corresponding to a current quark mass of 5 MeV. We test our ideas by calculating, to first order of the gluon-exchange interaction, the pion decay constant and the vector and axial-vector form factors for pion radiative decay. In our model the pion decay constant satisfies the PCAC requirement that it has a finite value in the limit of zero-mass pion.

• Research Organization: Department of Physics, Laval University, Sainte-Foy, Quebec, Canada G1K7P4
• OSTI ID: 7000797
• Journal Information: Phys. Rev. D; (United States), Journal Name: Phys. Rev. D; (United States) Vol. 29:7; ISSN PRVDA
• Country of Publication: United States
• Language: English

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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BAG MODEL
BOSONS
CHIRAL SYMMETRY
COMPOSITE MODELS
COUPLING CONSTANTS
ELEMENTARY PARTICLES
EQUATIONS
EXCHANGE INTERACTIONS
EXTENDED PARTICLE MODEL
FIELD THEORIES
FUNCTIONS
GLUONS
HADRONS
INTERACTIONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
MESONS
PARTICLE MODELS
PCAC THEORY
PIONS
POSTULATED PARTICLES
PSEUDOSCALAR MESONS
QUANTUM CHROMODYNAMICS
QUANTUM FIELD THEORY
QUARK MODEL
RADIATIVE DECAY
SUM RULES
SYMMETRY
SYMMETRY BREAKING
WAVE FUNCTIONS