Nonvanishing tensor polarization of sea quarks in polarized deuterons

We propose two new sources of a substantial tensor polarization of sea partons in the deuteron: the diffractive nuclear shadowing which depends on the alignment of nucleons in the polarized deuteron and the nuclear excess of pions in the deuteron which is sensitive to the spin state of the deuteron. The corresponding tensor structure function $b_{2}(x,Q^{2})$ rises towards small $x$ and we predict an about one per cent tensor asymmetry $A_{2}(x,Q^{2})=b_{2}(x,Q^{2})/ F_{2d}(x,Q^{2})$ which by almost two orders in magnitude exceeds the effect evaluated earlier in the impulse approximation. The both mechanisms for tensor structure function break the sum rule $\int dx b_{1}(x,Q^{2})=0$ suggested by Close and Kumano. We comment on the impact of tensor polarization on the determination of the vector spin structure function $g_{1d}(x,Q^{2})$ for the deuteron.