The space-time scales of the hadronization process in the framework of the string model are investigated. It is shown that the average formation lengths of pseudoscalar mesons, produced in semi-inclusive deep inelastic scattering of leptons on different targets, depend on their electrical charges. In particular, the average formation lengths of positively charged hadrons are larger than those of negatively charged ones. This statement is fulfilled for all scaling functions used, for $z$ (the fraction of the virtual photon energy transferred to the detected hadron) larger than $0.15$, for all nuclear targets, and for any value of the Björken scaling variable $x_{\mathrm{Bj}}$. In all cases, the main mechanism is direct production of pseudoscalar mesons. Including in consideration an additional mechanism of production resulting in decay of resonances leads to a decrease in average formation lengths. It is shown that the average formation lengths of positively (negatively) charged mesons are slowly increasing (decreasing) functions of $x_{\mathrm{Bj}}$. The results obtained can be important, in particular, for understanding of the hadronization process in the nuclear environment.

• Received 4 February 2010

DOI:https://doi.org/10.1103/PhysRevC.81.045207