We point out that perturbative evolution in QCD at three loops generates a strange-antistrange asymmetry $s(x)-\overline{s}(x)$ in the nucleon’s sea just from the fact that the nucleon has nonvanishing up and down quark valence densities. The recently computed three-loop splitting functions allow for an estimate of this effect. We find that a fairly sizable asymmetry may be generated. Results for analogous asymmetries in the heavy-quark sector are also presented.

• Received 6 May 2004

DOI:https://doi.org/10.1103/PhysRevLett.93.152003