Diquark model of the baryon spectrum

Technical Report · Sun May 01 04:00:00 EDT 1983

OSTI ID:5737464

Haire, M L

The presence of a coherent diquark structure within baryons has been suggested, both as a computational tool for simplifying some types of baryon calculations, and as an explanation for scaling violations in deep inelastic scattering. In this paper we consider the implications of the diquark hypothesis for baryons spectroscopy. Treating the diquark as an s-wave bound state of two quarks reduces the problem of three-body quark excitations within baryons to that of a two-body quark-diquark interaction. The spin-dependent excitation levels of the quark-diquark system can then be calculated in perturbative QCD, using a non-relativistic one-gluon-exchange approximation. The spectrum generated by this model differs from the conventional symmetric quark model spectrum in several crucial respects. Firstly, spin-orbit mass splitting between baryons is easily accommodated in the diquark picture, unlike the conventional model, where it must be cancelled ad hoc in order to obtain a reasonable fit to the mass spectrum. Secondly, the QCD parameters needed to fit the baryon spectrum in the diquark model are essentially the same as those used in the meson spectrum. This allows us to give a unified description of spin-dependent forces in mesons and baryons, which has not been possible in the symmetric quark model. We conclude with a qualitative discussion of spin-independent (multiple gluon exchange) forces in the diquark model, using effective confining potentials of the form, V(r) approx. r/sup n/. 28 references.

• Research Organization: Tufts Univ., Medford, MA (USA)
• DOE Contract Number: AC02-83ER40085
• OSTI ID: 5737464
• Report Number(s): DOE/ER/40085-4; ON: DE84000838
• Country of Publication: United States
• Language: English

Related Subjects

645206* -- High Energy Physics-- Particle Interactions & Properties-Theoretical-- Strong Interactions
Baryon No. = 1-- (-1987)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANGULAR MOMENTUM
BARYON RESONANCES
BARYON SPECTROSCOPY
BARYONS
BOUND STATE
COMPOSITE MODELS
ELEMENTARY PARTICLES
ENERGY LEVELS
EXCITED STATES
FERMIONS
FIELD THEORIES
FUNCTIONS
GLUONS
HADRONS
MASS SPECTRA
MATHEMATICAL MODELS
MULTIPLETS
PARTIAL WAVES
PARTICLE MODELS
PARTICLE PROPERTIES
POSTULATED PARTICLES
QUANTUM CHROMODYNAMICS
QUANTUM FIELD THEORY
QUARK MODEL
QUARKONIUM
RESONANCE PARTICLES
S WAVES
SPECTRA
SPECTROSCOPY
SPIN
WAVE FUNCTIONS