New Relations and Constraints on Quark Spin-flavor Contents in Symmetry-breaking Chiral Quark Model

Abstract

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, $\hat{I}{”}_3$ and $\hat{I}{”}_8$, all spin-flavor observables are functions of only one parameter $a$ $-$ probability for the chiral pionic fluctuation. The upper and lower bounds of these observables are given. The optimal range of $a$, determined by NMC data $\bar{d}-\bar{u}$, gives a constraint to the cutoff of the chiral quark field theory. The model predictions are in good agreement with the existing data in this range of $a$. The roles of kaon, $\hat{I}\cdot$ and $\hat{I}{\cdot }^{\prime }$ are also discussed.

20 pages, Revtex, 3 tables, 4 figures