Measurements of Double-Spin Asymmetries in SIDIS of Longitudinally Polarized Leptons off Transversely Polarized Protons

A Fourier analysis of double-spin azimuthal asymmetries measured at HERMES in semi-inclusive deep-inelastic scattering of longitudinally polarized leptons off tranversely polarized protons is presented for pions and charged kaons. The extracted amplitudes can be interpreted as convolutions of transverse momentum-dependent distribution and fragmentation functions and provide sensitivity to, e.g., the poorly known worm-gear quark distribution.