Second moment of quark structure function of the rho-meson in QCD sum rules

The second moments of the quark structure functions of the longitudinally and transversally polarized rho-mesons are calculated in the framework of QCD sum rules in external fields. Operators of dimension 4 and 6 are taken into account. The results are: 0.84 for the longitudinal polarization, 0.5 for the transversal polarization. The large difference between these values indicates that the rho-meson polarization strongly influences the internal structure. In particular, in the case of the longitudinally polarized rho-meson the gluon sea is found to be strongly suppressed, it is less than 0.20 - 0.25, whereas in usual hadron case -- about 0.4 - 0.5.