Self-consistent calculation of parton distributions at low normalization point in the chiral quark-soliton model

We calculate the isosinglet unpolarized quark-- and antiquark distributions at a low normalization point in the large–$N_c$ limit. The nucleon is described as a self-consistent soliton solution of the effective chiral theory. The ultraviolet cutoff is implemented by a Pauli-Villars subtraction. The quark and antiquark distributions satisfy the momentum as well as the baryon number sum rule, corresponding to ``constituent’’ quarks whose structure is not yet resolved at the low scale. Already at this level a sizable number of antiquarks is present.