Partially conserved axial-current, noncanonicality and the sigma commutator
The pion nucleon sigma commutator, sigma(..pi..N), is studied using the quark mass term as the mechanism for chiral symmetry breaking. The resulting expression for the divergence of the axial-vector current is not a canonical field as conjectured in the hypothesis of partially conserved axial-vector current. This produces a significant modification of the relationship between the soft pion limit of isoscalar pion nucleon scattering amplitude and sigma(..pi..N). Thus the analysis of ..pi..N scattering data yields not the true sigma commutator but what we call the apparent sigma commutator, sigma/sub A/. The latter is a sum of sigma(..pi..N) and a contribution from the noncanonicality of the divergence of the axial-vector current. A pionically amended quark bag model (the Cloudy Bag Model) is used to calculate sigma/sub A/. The Cloudy Bag Model with its bag radius of 0.82 fm can be sigma/sub A/ = 25 MeV, the result of one of the recent studies of the quantity, with 7.7 MeV as the mean mass of u and d quarks.
- Research Organization:
- Washington Univ., Seattle (USA); Maryland Univ., College Park (USA). Dept. of Physics and Astronomy
- DOE Contract Number:
- AS05-76ER05126; AC06-76ER01388
- OSTI ID:
- 6479283
- Report Number(s):
- DOE/ER/05126-T2; RLO-1388-856; ORO-5126-135; ON: DE81023283
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Baryon No. = 0-- (-1987)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMPLITUDES
BAG MODEL
CHIRALITY
COMPOSITE MODELS
DATA
EXTENDED PARTICLE MODEL
HADRON-HADRON INTERACTIONS
INFORMATION
INTERACTIONS
MATHEMATICAL MODELS
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
NUMERICAL DATA
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE PROPERTIES
PION-NUCLEON INTERACTIONS
QUARK MODEL
SCATTERING AMPLITUDES
SIGMA MODEL
SYMMETRY BREAKING
THEORETICAL DATA