Nucleon wave function with running quark masses

Three-quark nucleon wave function is constructed within the light-front framework. Quarks have running masses, which interpolate between the constituent and the current quark mass. In the spinor part of our model wave function all three Ioffe spin structures are needed. They are also required in the nucleon spinor currents in the QCD sum rules, if one asks for the maximal overlap with the state of the physical nucleon. In our calculations, the presence of three Ioffe spin structures is necessary to get simultaneously the negative value for the neutron charge radius and the descreasing d/u ratio in proton, which are well established experimental results. Selecting the coefficients in front of the Ioffe spin structures as: 1, 1.4 and 2.3 and the shape of a Gaussian distribution in the transverse momenta about 40% broader than that of the Isgur and Karl model, we get: neutron = -0.11 fm2, proton = 0.74 fm2, μn-eutron = -1.7, μproton = 2.8, GA/GV = 1.1, and the decreasing d/u ratio in proton's deep inelastic scattering, if xBj is increasing toward 1. 23 refs., 2 figs., 1 tab. (author)