Polarization of partons in the proton

The spin-dependent distribution functions of quarks and gluons in a proton are studied so as to explain the European Muon Collaboration $g_1^p\mathrm{}\left(x\right)\mathrm{}$ data by introducing a new model, in which characteristics of both the static quark and the quark-parton model are taken into account. The $x$ dependence of $g_1^p\mathrm{}\left(x\right)\mathrm{}$ is reproduced well. It is shown that polarized gluons through the anomaly play a significant role and the resultant sum of quark spin is 0.375. Furthermore, $g_1^n\mathrm{}\left(x\right)\mathrm{}$ as well as $g_1^p\mathrm{}\left(x\right)\mathrm{}$ is predicted for future experiments.