A new determination of polarized parton densities in the nucleon

In order to determine polarized parton distributions we have made a new NLO QCD fit using all experimental data on spin asymmetries measured in the deep inelastic scattering on different nucleon targets. The functional form of such densities is based on MRST 2001 results for unpolarized ones . We get for polarization of quarks (at Q^2 = 1 GeV^2): Delta u = 0.87, Delta d = -0.38, Delta s = -0.04. The total quark polarization is rather big and we obtain: Delta Sigma = 0.44. As a result of our fit we get a_3 = g_A = 1.24 the value which is close to experimental number. With negligible Delta s and rather big Delta Sigma (comparable to a_8) the results of our new fit are quite different in character from other fits.