Rapidity distribution of particle multiplicity in DIS at small x

Analytical study of the rapidity distribution of the final state particles in deep inelastic scattering at small x is presented. We separate and analyze three sources of particle production: fragmentation of the quark–antiquark pair that these an impact, accompanying coherent soft gluon radiation due to octet color exchange in the t-channel, and fragmentation of gluons that form parton distribution functions. Connection to Catani–Ciafaloni–Fiorani–Marchesini (CCFM) equations and the role of gluon reggeization are also discussed.