TIME-REVERSAL ODD FRAGMENTATION FUNCTIONS IN SEMIINCLUSIVE SCATTERING OF POLARIZED LEPTONS FROM UNPOLARIZED HADRONS

Semi-inclusive deep inelastic scattering of polarized leptons off hadrons enables one to measure the antisymmetric part of the hadron tenser. For unpolarized hadrons this piece is odd under time reversal. In deep inelastic scattering it shows up as a (sin phi) asymmetry for the produced hadrons. This asymmetry can be expressed as the product of a twist-three ''hadron --> quark'' distribution function and a time reversal odd twist-two ''quark --> hadron'' fragmentation function. This fragmentation function can only be measured for nonzero transverse momenta of the produced hadron.