Quark-diquark breaking of baryon symmetry

Thesis/Dissertation · Tue Jan 01 00:00:00 EST 1980

OSTI ID:6236718

De Souza, M M

We assume that baryons are made of quark-diquark pairs, in the sense that two of the quarks inside the baryons are more closely bound than they are to the third one. This enlarges the SU(6) baryon symmetry into (SU(6))/sub quark/ x (SU(6))/sub diquark/. This is the symmetry of our free quark-diquark Hamiltonian. We write its eigenstates as the direct product of quark and diquark states. This symmetry is broken into (SU(2) x SU(3))/sub quark/ x (SU(2) x SU(3))/sub diquark/, by quark-quark interactions, assumed to be mediated by an octet of gluons transforming like vector mesons. It is broken further by interactions transforming like the eighth and the third SU(3) generators, and by electrostatic interactions. We assume that a parameter sigma describes the strength of the quark-diquark effects; in the limit of sigma = 0, the symmetry reduces to SU(6) and its usual breakings. In the limit of sigma = 0, we fit the ground state masses to within 1% of the experimental data, except for the ..delta..(1232) where the error is 2.14%. We then expand the mass formulas in terms of sigma, keeping terms only up to the second order, to show that the error in the ..delta..(1232) mass is reduced to .67%. We write the magnetic moments, ..mu../sub p/ and ..mu../sub n/, the axial and vector couplings, g/sub A/ and g/sub V/ for the nucleons in terms of sigma. We solve these equations, taking the ratios of axial and vector coupling g/sub A//g/sub V/ = 1.253 as input and the nucleon mixing angle Theta as a parameter, to find ..mu../sub p//..mu../sub n/ = -1.46, sigma = -0.1833, Theta = 15.33/sup 0/, and g/sub V/ = 1.044. These numbers give a good fit to the experimental value for the calculated magnetic moment of ..lambda..,..mu../sub n/.

• Research Organization: Maryland Univ., Baltimore (USA)
• OSTI ID: 6236718
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BARYONS
QUARK MODEL
SYMMETRY BREAKING
LAMBDA-1405 RESONANCES
MAGNETIC MOMENTS
DELTA-1236 RESONANCES
EIGENSTATES
GLUONS
HAMILTONIANS
MASS
QUARKS
SU-2 GROUPS
SU-3 GROUPS
SU-6 GROUPS
THEORETICAL DATA
VECTOR MESONS
BARYON RESONANCES
BOSONS
COMPOSITE MODELS
DATA
ELEMENTARY PARTICLES
FERMIONS
HADRONS
INFORMATION
LIE GROUPS
MATHEMATICAL MODELS
MATHEMATICAL OPERATORS
MESON RESONANCES
MESONS
N RESONANCES
NUMERICAL DATA
PARTICLE MODELS
POSTULATED PARTICLES
QUANTUM OPERATORS
RESONANCE PARTICLES
SU GROUPS
SYMMETRY GROUPS
Y RESONANCES
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