A chiral theory of light-flavor sea-quark distributions in the nucleon

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 ∆ms 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 light-flavor seaquark asymmetry as exemplified by the observables d̄(x)− ū(x), d̄(x)/ū(x),∆ū(x)−∆d̄(x) as well as on the particle-antiparticle asymmetry of the strange quark distributions represented by s(x)− s̄(x), s(x)/s̄(x),∆s(x)−∆s̄(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 d̄(x)− ū(x), the E866 data for d̄(x)/ū(x), the CCFR data and Barone et al.’s fit for s(x)/s̄(x) etc. The model is shown to give several unique predictions also for the spin-dependent sea-quark distribution, such that ∆s(x) ≪ ∆s̄(x) . 0 and ∆d̄(x) < 0 < ∆ū(x), although the verification of these predictions must await more elaborate experimental investigations in the near future. Email : [email protected] 1