Light-flavor sea-quark distributions in the nucleon in the SU(3) chiral quark soliton model (I) -- phenomenological predictions --

Abstract

Theoretical predictions are given for the light-flavor sea-quark distributions including the strange quark ones on the basis of the flavor SU(3) version of the chiral quark soliton model. Careful account is taken here of the SU(3) symmetry breaking effects due to the mass difference between the strange and nonstrange quarks. This effective mass difference $\Delta m_s$ between the strange and nonstrange quarks is the only one parameter necessary for the flavor SU(3) generalization of the model. A particular emphasis of study is put on the {\it light-flavor sea-quark asymmetry} as exemplified by the observables $\bar{d}(x)-\bar{u}(x),\bar{d}(x)/\bar{u}(x),\Delta \bar{u}(x)-\Delta \bar{d}(x)$ as well as on the {\it particle-antiparticle asymmetry} of the strange quark distributions represented by $s(x)-\bar{s}(x),s(x)/\bar{s}(x),\Delta s(x)-\Delta \bar{s}(x)$ etc. As for the unpolarized sea-quark distributions, the predictions of the model seem qualitatively consistent with the available phenomenological information provided by the NMC data for $\bar{d}(x)-\bar{u}(x)$, the E866 data for $\bar{d}(x)/\bar{u}(x)$, the CCFR data and Barone et al.'s fit for $s(x)/\bar{s}(x)$ etc. The model is shown to give several unique predictions also for the spin-dependent sea-quark distribution, such that $\Delta s(x)\ll \Delta \bar{s}(x)\lesssim 0$ and $\Delta \bar{d}(x)<0<\Delta \bar{u}(x)$, although the verification of these predictions must await more elaborate experimental investigations in the near future.

Comments: 36 pages, 20 EPS figures. The revised version accepted for publication in Phys. Rev. D. The title has been changed, and the body of the paper has been divided into two pieces, i.e.. the present one which discusses the main phenomenological predictions of the model and the other one which describes the detailed formulation of the flavor SU(3) chiral quark soliton model to predict light-flavor quark and antiquark distribution functions in the nucleon