Quark distributions in QCD sum rules: unexpected features and paradoxes
  Some very unusual features of the hadron structure functions, obtained in the generalized QCD sum rules, like the surprisingly strong difference between longitudinally and transversally polarized $\rho$ mesons structure functions and the strong suppression of the gluon sea in longitudinally polarized $\rho$ mesons are discussed. Also the problem of exact zero contribution of gluon condensates to pion and longitudinally polarized $\rho$ meson quark distributions is discussed. 
A.G.Oganesian