Double-spin cosφ asymmetry in semi-inclusive electroproduction

We consider the double-spin cosφ asymmetry for pion electroproduction in semi-inclusive deep inelastic scattering of longitudinally polarized leptons off longitudinally polarized protons. We estimate the size of the asymmetry in the approximation where all twist-3 interaction-dependent distribution and fragmentation functions are set to zero. In that approximation at HERMES kinematics a sizable negative cosφ double-spin asymmetry for π+ electroproduction is predicted.