Formation lengths of hadrons in lepto-production
  The average formation lengths of the hadrons produced during the deep inelastic scattering (DIS) of leptons on protons are studied in the framework of the symmetric Lund model. It is shown that these formation lengths essentially depend on the electric charges of the hadron. For electro-production and charged current (CC) neutrino-production, the average formation lengths of positively charged particles are larger than those of negatively charged antiparticles. This situation is reversed for CC antineutrino-production. In all the mentioned cases, the main mechanism is the direct production of hadrons. The additional mechanism of hadron production, through the decay of resonances, is essential only for pions and leads to a decrease in the average formation lengths. 
Levon Grigoryan
hep-ph