Integrated spin structure function of the nucleon using extended Fock space approach

Abstract

We study the effect of sea quarks on the integrated spin structure functions, the F/D ratio and the total quark polarization, , of the nucleon. The extended Fock space approach is used to incorporate the sea quarks and its wavefunction is properly antisymmetrized. These configurations give significant contributions to the integrated spin structure functions. In particular, antisymmetrization is found to play an important role in the case of the integrated spin structure function of the neutron and the F/D ratio. We find good agreement with experimental values for all four spin polarization observables. I IntroductionThe integrated spin structure function of the neutron (I L ), extracted from recent experiments [1, 2] underline the inadequacy of the naive three quark model of nucleon. The values of I L obtained are quite dissimilar in these two experiments. However, both groups obtain a negative value for this quantity. Theoretically, the value of I L vanishes in the naive quark model due to the symmetry of Sº(6) wavefunction (wf ). Admixtures of other symmetry states like mixed-symmetry and D state lead to a non-zero value. However, similar calculations performed in the bag model with three quarks [3] predicts a positive value of I L . We arrive at the same conclusion. Thus, in order to explain the negative value of I L , it is necessary to extend the Fock-space and include configurations of sea quark wf.The extended Fock-space method has been used in a diverse range of problems. This approach led to the conclusion that the q-qN (sea) degrees of freedom should be included in a proper description of the baryons [4]. Earlier applications of this method include the Nscattering [5] and N-N scattering [6]. We have also used this method to find a natural explanation for the negative strange sea polarization in the proton [7]. This method has also been used by Jaffe and Lipkin [8].