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Title: Understanding the flavor symmetry breaking and nucleon flavor-spin structure within the chiral quark model

Abstract

In {chi}QM, a quark can emit Goldstone bosons. The flavor symmetry breaking in the Goldstone boson emission process is used to interpret the nucleon flavor-spin structure. In this paper, we study the inner structure of constituent quarks implied in {chi}QM caused by the Goldstone boson emission process in nucleon. From a simplified model Hamiltonian derived from {chi}QM, the intrinsic wave functions of constituent quarks are determined. Then the obtained transition probabilities of the emission of Goldstone boson from a quark can give a reasonable interpretation to the flavor symmetry breaking in nucleon flavor-spin structure.

Authors:
; ;  [1]
  1. Department of Physics, Peking University, Beijing 100871 (China)
Publication Date:
OSTI Identifier:
21020490
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 9; Other Information: DOI: 10.1103/PhysRevD.75.094018; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CHIRALITY; FLAVOR MODEL; GOLDSTONE BOSONS; HAMILTONIANS; NUCLEONS; PARTICLE STRUCTURE; PROBABILITY; QUARK MODEL; QUARKS; SPIN; SYMMETRY BREAKING; WAVE FUNCTIONS

Citation Formats

Shu Zhan, Chen Xiaolin, and Deng Weizhen. Understanding the flavor symmetry breaking and nucleon flavor-spin structure within the chiral quark model. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.094018.
Shu Zhan, Chen Xiaolin, & Deng Weizhen. Understanding the flavor symmetry breaking and nucleon flavor-spin structure within the chiral quark model. United States. doi:10.1103/PHYSREVD.75.094018.
Shu Zhan, Chen Xiaolin, and Deng Weizhen. Tue . "Understanding the flavor symmetry breaking and nucleon flavor-spin structure within the chiral quark model". United States. doi:10.1103/PHYSREVD.75.094018.
@article{osti_21020490,
title = {Understanding the flavor symmetry breaking and nucleon flavor-spin structure within the chiral quark model},
author = {Shu Zhan and Chen Xiaolin and Deng Weizhen},
abstractNote = {In {chi}QM, a quark can emit Goldstone bosons. The flavor symmetry breaking in the Goldstone boson emission process is used to interpret the nucleon flavor-spin structure. In this paper, we study the inner structure of constituent quarks implied in {chi}QM caused by the Goldstone boson emission process in nucleon. From a simplified model Hamiltonian derived from {chi}QM, the intrinsic wave functions of constituent quarks are determined. Then the obtained transition probabilities of the emission of Goldstone boson from a quark can give a reasonable interpretation to the flavor symmetry breaking in nucleon flavor-spin structure.},
doi = {10.1103/PHYSREVD.75.094018},
journal = {Physical Review. D, Particles Fields},
number = 9,
volume = 75,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
  • The SU(3) symmetric chiral quark model, which describes interactions between quarks, gluons, and the Goldstone bosons, explains reasonably well many aspects of the flavor and spin structure of the proton, except for the values of f{sub 3}/f{sub 8} and {Delta}{sub 3}/{Delta}{sub 8}. Introducing the SU(3)-breaking effect suggested by the mass difference between the strange and nonstrange quarks, we find that this discrepancy can be removed and better overall agreement obtained. {copyright} {ital 1997} {ital The American Physical Society}
  • New relations between the quark spin-flavor contents of the nucleon and axial weak coupling constants are obtained in the chiral quark model with both SU(3)- and U(1)-breaking effects. Using the nonsinglet spin combinations {Delta}{sub 3} and {Delta}{sub 8}, all spin-flavor observables are functions of only one parameter a{emdash}the probability for the chiral pionic fluctuation. The upper and lower bounds of these observables are given. The optimum range of a, determined by NMC data {bar d}{minus}{bar u}, gives a constraint to the cutoff of the chiral quark field theory. The model predictions are in good agreement with the existing data inmore » this range of a. The roles of the kaon, {eta} and {eta}{sup {prime}} are also discussed. {copyright} {ital 1998} {ital The American Physical Society}« less
  • A simple calculation in the framework of the chiral quark theory of Manohar and Georgi yields results that can account for many of the ``failures`` of the naive quark model: significant strange quark content in the nucleon as indicated by the value of {sigma}{sub {pi}{ital N}}, the {ital d}{ovr bar} a symmetry in the nucleon as measured by the deviation from the Gottfried sum rule and by the Drell-Yan process, as well as the various quark contributions to the nucleon spin as measured by deep inelastic polarized lepton-nucleon scattering.
  • The chiral quark model with a nonet of Goldstone bosons can yield an adequate description of the observed proton flavor and spin structure. In a previous publication we have compared the results of an SU(3) symmetric calculation with the phenomenological findings based on experimental measurements and SU(3) symmetry relations. In this paper we discuss their SU(3) and axial U(1) breaking corrections. Our result demonstrates the broad consistency of the chiral quark model with the experimental observations of the proton spin-flavor structure. With two parameters, we obtain a very satifactory fit to the F/D ratios for the octet baryon masses andmore » for their axial vector couplings, as well as the different quark flavor contributions to the proton spin. The result also can account for not only the light quark asymmetry {bar u}{minus}{bar d} but also the strange quark content {bar s} of the proton sea. SU(3) breaking is the key in reconciling the {bar s} value as measured in the neutrino charm production and that as deduced from the pion nucleon {sigma} term. {copyright} {ital 1997} {ital The American Physical Society}« less
  • The flavor-asymmetry in the light-quark sea of the nucleon can be obtained from the contributions of unbroken sea quark distributions. We employ the polarized valon model in based on Jacobi polynomial approach and extract the flavor-broken light sea quark distributions which are modeled with the help of a Pauli-blocking ansatz. Our results for {delta}u, {delta}d, {delta}u-bar, {delta}d-bar and {delta}s-bar are in good agreement with recent experimental data for polarized parton distribution from HERMES experimental group and also with GRSV model.