text: The leading hadron results from the hadronization of the struck quark. This latter retains the information on its motion inside the nucleon, including its transverse momentum which allows to access the transverse momentum distributions (TMDs) of partons.
  Likewise, by detecting the leading hadron, one essentially tags (i.e. identifies) the quark on which the scattering occurred. For example, if the leading hadron is a kaon, we know that the scattering occurred on one of the strange quarks of the nucleon's quark sea. In DIS the struck quark is not identified and the information is an indistinguishable sum over all the quark flavors. SIDIS allows to disentangle this information.