Nonvanishing tensor polarization of sea quarks in polarized deuterons

We show how the dependence of the diffractive nuclear shadowing and of the nuclear excess of pions on the deuteron spin alignment leads to a substantial tensor polarization of sea partons in the deuteron. The corresponding tensor structure functionb₂ (x, Q²) rises towards small x and we predict the about one per cent tensor asymmetryA₂ (x, Q²) = b₂ (x, Q²) /F_2d (x, Q²) which by almost two orders in magnitude exceeds the effect evaluated earlier in the impulse approximation. We show that the integral ƒ;¹₀ dx b₁ (x, Q²) diverges, which implies that the sum rule ƒ;¹₀ dx b₁ (x, Q²) = 0 suggested by Close and Kumano does not exist. We comment on the impact of tensor polarization on the determination of the vector spin structure functiong_1d (x, Q²) for the deuteron.