The internal structure of the jets produced in neutral current interactions for Q^2>125 GeV^2 has been studied using the subjet multiplicity with the ZEUS detector at HERA. Jets are identified in the laboratory frame by applying the longitudinally invariant k_T-cluster algorithm. Next-to-leading order QCD calculations have been obtained and compared to the data; a good agreement has been observed in the region where hadron-to-parton corrections are small, E_{ T,jet}> 25 GeV. In this region, the strong coupling constant is extracted and the resulting value is alpha_s (M_Z)=0.1185 +/- 0.0016 (stat.) ^{ +0.0067}_{ -0.0048} (syst.) ^{ +0.0089}_{ -0.0071} (th.).
Categories: hep-ex