Search

We investigate the breaking of flavour symmetry, quark-antiquark symmetry and charge symmetry by the nucleon''s parton distributions in the unpolarized and the polarized nucleon sea using the meson cloud model. We find that the SU(2) flavour symmetry breaking in the polarized nucleon sea is much smaller than in the unpolarized nucleon sea. The strange-antistrange symmetry is found to be broken in both the unpolarized and the polarized nucleon sea. Our calculations for the parton distributions in the polarized nucleon sea are in agreement with the recent results from the HERMES Collaboration which uses semi-inclusive DIS to make a flavour decomposition of spin dependent scattering data. The charge symmetry breaking is found to be small. [Copyright &y& Elsevier]