Read-head Conditions for Obtaining Areal Recording Density of 5.8 Tbit/in.² on a Bit-Patterned Medium

Abstract

The second moments of the quark structure functions of the longitudinally M L ρ and transversally M T ρ polarized ρ-mesons are calculated in the framework of QCD sum rules in external fields. The operators of dimension 4 and 6 are taken into account. The results are (µ 2 = 1 GeV 2 ): M L ρ = 0.84 ± 0.08, M T ρ = 0.5 ± 0.1. The large difference between the values of M L ρ and M T ρ indicates that the ρ-meson polarization strongly influences the internal structure. In particular, in the case of the longitudinally polarized ρ-meson the gluon sea is found to be strongly suppressed, it is less than 20 ÷ 25%, whereas in usual hadron case -about 40 ÷ 50%.