Parton distributions at low x and gluon- and quark average multiplicities

Abstract

We shown the general approach for Q2 evolution of parton densities and fragmentation functions at low x based on the diagonalization. The diagonalization leads to the two components in the Q2 evolution, each of which contains a nonperturbative parameter. The values of the parameters can be found by fits of the experimental data for the deep-inelastic scattering structure function F2 and for average jet multiplicities. One of the components contains the all large logarithms ln(1/x) and produce the basic contribution at small x region. The second one is regular at low x but its contribution is very important to have a good agreement with experimental data

Comments: 40 pages, 6 figures, PoS(Baldin ISHEPP XXII)028, talk given on XII International Baldin Seminar "Relativistic Nuclear Physics and Quantum Chromodynamics", September 15 - 20, Dubna, 2014