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

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