SU(6) strong breaking: structure functions and static properties of the nucleon

Journal Article · Wed Oct 01 04:00:00 EDT 1975 · Phys. Rev., D, v. 12, no. 7, pp. 2137-2156

DOI:https://doi.org/10.1103/PhysRevD.12.2137· OSTI ID:4083652

Le Yaouanc, A; Oliver, L; Pene, O; Raynal, J

In order to explain the experimental x behavior of the ratio of deep- inelastic scattering structure functions F$sub 2$/sup en//F$sub 2$/sup ep/, which is a manifestation of SU(6) breaking, we propose to introduce, in the harmonic- oscillator quark model, the following interband mixing for the nucleon wave function at rest: cos phi(56,0$sup +$)/sub N = 0/ + sin phi(70,0$sup +$)/sub N = 1/. The effect on the x behavior of the ratio F$sub 2$/sup en//F$sub 2$/sup ep/ is linear in tan phi; the angle is found to be phi approx. = -20$sup 0$. It turns out that the famous successes of unbroken SU(6) for the low-lying--octet static properties are not broken significantly, $mu$/sub p//sup tot//$mu$/sub n// sup tot/approx. = -3(1+0.03)/2, (F/D)/sub axial-vector/ approx. = 2(1+0.02)/3, since the breaking effect is proportional to tan$sup 2$phi with reducing coefficients. Moreover, the mixing implies a slope for the neutron electric form factor, which is a linear effect in tan phi, of the right sign and order of magnitude. The abs. value of G/sub A//G/sub V/ is correctly predicted to be 1.25. The chiral configuration mixing describing the nucleon wave function at P/sub z/ = infinity is shown to come from the combination of two effects: (i) introduction of small components in the quark Dirac spinors to account for the highly relativistic internal quark velocities as described in our previous papers, which preserves the 56 assignment of the nucleonwave function at rest, and (ii) the new effect of SU(6) mixing for the nucleon wave function at rest. Introducing a structure for the quarks which parallels the need for quark structure in the leptoproduction of hadrons, we end with a good description of the unpolarized structure functions in deep-inelastic electro- and neutrino production. Further predictions are made of the yet-unmeasured asymmetries in deep-inelastic polarized electroproduction. (AIP)

• Research Organization: Laboratoire de Physique Theorique et Hautes Energies, Universite de Paris-Sud, 91405 Orsay, France
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-015807
• OSTI ID: 4083652
• Journal Information: Phys. Rev., D, v. 12, no. 7, pp. 2137-2156, Journal Name: Phys. Rev., D, v. 12, no. 7, pp. 2137-2156; ISSN PRVDA
• Country of Publication: United States
• Language: English

Related Subjects

*ELECTROPRODUCTION-- STRUCTURE FUNCTIONS
*NUCLEONS-- WAVE FUNCTIONS
*SU-6 GROUPS-- SYMMETRY BREAKING
641102*
CONFIGURATION MIXING
COUPLING CONSTANTS
HARMONIC OSCILLATOR MODELS
ISOSPIN
LEPTON-NUCLEON INTERACTIONS
N64220* --Physics (High Energy)--Particle Interactions & Properties (Theoretical)--Electromagnetic
QUARK MODEL
SPIN ORIENTATION
SPINORS