delta. /sub 33/ resonance in pion nucleus elastic, single, and double charge exchange scattering

Conference · Sat Jan 01 04:00:00 EST 1983

OSTI ID:6042174

Johnson, M B

The ..delta../sub 33/ resonance is strongly excited in pion-nucleon scattering, but there is clearly only a limited amount of information that can be learned in scattering the pion from an isolated nucleon. One learns that there is a resonance of mass 1232 MeV, width 115 MeV, and, if one is willing to introduce a dynamical model, something about the off-shell extension of the amplitude. One stands to learn much more from pion-nucleus scattering because in this case the ..delta../sub 33/ resonance has an opportunity to scatter from nucleons, and how this occurs is not well understood. What do we know about the ..delta..-N interaction for pion-nucleus scattering. The isobar-hole model was invented to deal directly with the ..delta../sub 33/-nucleus dynamics, and a phenomenological determination of the isobar shell-model potential was attempted. The unknown dynamics deltaU/sub ..delta../ is contained in a central isoscalar spreading potential of strength W/sub 0/ and a spin orbit potential deltaU/sub 0/ = W/sub 0/rho + spin-orbit. The real part of W/sub 0/rho is measured relative to the nucleon-nucleus potential. From a more theoretical point of view, one would like to be able to calculate deltaU/sub ..delta../, including its isospin dependence, from an underlying dynamical model which is formulated in terms of the basic effective meson-baryon couplings. Some salient properties of these couplings can be determined from models of quark-bag structure, which raises the exciting possibility of learning about these fundamental issues from pion scattering. Attempts at Los Alamos to build a theoretical framework to deal with these and other issues are described. (WHK)

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6042174
• Report Number(s): LA-UR-83-1725; CONF-830588-2; ON: DE83014119
• Country of Publication: United States
• Language: English

Related Subjects

653003* -- Nuclear Theory-- Nuclear Reactions & Scattering
653007 -- Nuclear Theory-- Nuclear Models-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYON RESONANCES
BARYONS
BASIC INTERACTIONS
CHARGE-EXCHANGE INTERACTIONS
CHARGED-PARTICLE REACTIONS
COUPLING
CROSS SECTIONS
DELTA-1236 RESONANCES
ELASTIC SCATTERING
ELEMENTARY PARTICLES
FERMIONS
HADRON REACTIONS
HADRONS
INTERACTIONS
ISOBAR MODEL
ISOSPIN
MATHEMATICAL MODELS
MESON REACTIONS
N RESONANCES
NUCLEAR MODELS
NUCLEAR POTENTIAL
NUCLEAR REACTIONS
PARTICLE MODELS
PARTICLE PROPERTIES
PION REACTIONS
POTENTIALS
RESONANCE PARTICLES
SCATTERING
SHELL MODELS
STRONG INTERACTIONS