Soft-pion correction to the Skyrmion, chiral vacuum effects in the bag and double-delta formation in pion absorption
Soft-pion corrections to the Skyrme-soliton are considered to one loop order. Starting from Weinberg's low-energy expansion, a consistent effective description to one-loop order is constructed which contains Skyrme's model in the classical limit. Soft-pion contributions to the nucleon and ..delta..-isobar masses are evaluated, and their relevance to baryon dynamics discussed. It is shown that under chiral SU(2) x SU(2) boundary conditions of the hedgehog type, the Dirac vacuum in the chiral bag model up non-trivial chiral terms. Double-..delta..(1232) formation following pion absorption on heavy nuclei in and above the (3,3) resonance region is compared to the standard ..pi..NN..--> delta..N..-->..NN two-nucleon process. This mechanism is shown to be a substantial, if the ..delta..N..--> delta delta.. interactions follows SU(4) quark model rules. It is able to explain some of the striking features observed in proton emission spectra following ..pi../sup +/-/-nucleus absorption in the ..delta.. resonance region. The double-..delta.. mechanism is further examined in the /sup 4/He(..pi..,4N) reaction. It is found that this mechanism contributes appreciably to the total absorption cross section in the energy range of 450-600 MeV.
- Research Organization:
- State Univ. of New York, Stony Brook (USA)
- OSTI ID:
- 5679196
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PION REACTIONS
CAPTURE
BAG MODEL
DELTA-1236 RESONANCES
HELIUM 4 TARGET
MEV RANGE 100-1000
RESONANCE
SKYRME POTENTIAL
SOLITONS
VACUUM STATES
CHARGED-PARTICLE REACTIONS
COMPOSITE MODELS
ENERGY RANGE
EXTENDED PARTICLE MODEL
HADRON REACTIONS
MATHEMATICAL MODELS
MESON REACTIONS
MEV RANGE
NUCLEAR REACTIONS
NUCLEON-NUCLEON POTENTIAL
PARTICLE MODELS
POTENTIALS
QUARK MODEL
QUASI PARTICLES
TARGETS
653003* - Nuclear Theory- Nuclear Reactions & Scattering