We show that a new beam-spin asymmetry appears in deep inelastic inclusive lepto-production at low transverse momenta when a hadron in the target fragmentation region is observed in association with another hadron in the current fragmentation region.
The beam leptons are longitudinally polarized while the target nucleons are unpolarized. This asymmetry is a leading-twist effect generated by the correlation between the transverse momentum of quarks and the transverse momentum of the hadron emitted by the target. Experimental signatures of this effect are discussed.
We study the inclusive production of two hadrons in deep inelastic processes, l N ---> l h_1 h_2 X, with h_1 in the current fragmentation region (CFR) and h_2 in the target fragmentation region (TFR). Assuming a factorized scheme, the recently introd
uced polarized and transverse momentum dependent fracture functions couple to the transverse momentum dependent fragmentation functions. This allows the full exploration of the fracture functions for transversely polarized quarks. Some particular cases are considered.
The target fragmentation region of semi-inclusive deep inelastic scattering is described at leading twist, taking beam and target polarizations into account. The formalism of polarized and transverse-momentum dependent fracture functions is developed
and the observables for some specific processes are presented.
