Soft-pion correction to the Skyrmion, chiral vacuum effects in the bag and double-delta formation in pion absorption

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5679196

Wirzba, A

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
• Country of Publication: United States
• Language: English

Related Subjects

653003* -- Nuclear Theory-- Nuclear Reactions & Scattering
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BAG MODEL
CAPTURE
CHARGED-PARTICLE REACTIONS
COMPOSITE MODELS
DELTA-1236 RESONANCES
ENERGY RANGE
EXTENDED PARTICLE MODEL
HADRON REACTIONS
HELIUM 4 TARGET
MATHEMATICAL MODELS
MESON REACTIONS
MEV RANGE
MEV RANGE 100-1000
NUCLEAR REACTIONS
NUCLEON-NUCLEON POTENTIAL
PARTICLE MODELS
PION REACTIONS
POTENTIALS
QUARK MODEL
QUASI PARTICLES
RESONANCE
SKYRME POTENTIAL
SOLITONS
TARGETS
VACUUM STATES