Charge Radii and Quadrupole Moments of the Low-Lying Baryons in the Chiral Constituent Quark Model

Harleen Dahiya,Neetika Sharma

doi:10.1155/2013/756847

Abstract

The chiral constituent quark model (χCQM) with general parameterization method (GPM) has been formulated to calculate the charge radii of the spin1/2+octet and3/2+decuplet baryons and quadrupole moments of the spin3/2+decuplet baryons and spin3/2+→1/2+transitions. The implications of such a model have been investigated in detail for the effects of symmetry breaking and GPM parameters pertaining to the one-, two-, and three-quark contributions. Our results are not only comparable with the latest experimental studies but also agree with other phenomenological models. It is found that theχCQM is successful in giving a quantitative and qualitative description of the charge radii and quadrupole moments.

Highlights

The internal structure of baryons is determined in terms of electromagnetic Dirac and Pauli form factors F1(Q2) and F2(Q2) or equivalently in terms of the electric and magnetic Sachs form factors GE(Q2) and GM(Q2) [1]
quantum chromodynamics (QCD) is accepted as the fundamental theory of strong interactions, the direct prediction of these kinds of observables from the first principle of QCD still remains a theoretical challenge as they lie in the nonperturbative regime of QCD
A best fit of χCQM parameters can be obtained by carrying out a fine grained analysis of the spin and flavor distribution functions [117,118,119] leading to a = 0.12, α = 0.7, β = 0.4, ζ = −0.15. (36)

Summary

Introduction

The internal structure of baryons is determined in terms of electromagnetic Dirac and Pauli form factors F1(Q2) and F2(Q2) or equivalently in terms of the electric and magnetic Sachs form factors GE(Q2) and GM(Q2) [1]. The electromagnetic form factors are the fundamental quantities of theoretical and experimental interest which are further related to the static low energy observables of charge radii and magnetic moments. It becomes interesting to discuss the interplay between the spin of nonvalence quark and the orbital angular momentum in understanding the spin structure of baryons. It is well known that the quadrupole moment of the nucleon should vanish on account of its spin-1/2 nature. This observation has naturally turned to be the subject of intense theoretical and experimental activity

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Results

Conclusion