Timelike structure functions and hadron multiplicities

Abstract

In this talk we discuss the results obtained in the new approach that we recently introduced to consider and include both the perturbative and nonperturbative contributions to the evolution of the gluon and quark avarage multiplicities. We report on our progresses in solving a longstanding puzzle of QCD. The new formalism is motivated by recent important theoretical developments in timelike small-x resummation which are also discussed mostly from an historical point of view. We have extended our global analysis to fit the available data adding the strong coupling constant as a fit parameter. In this way our best fit gives α s (M z ) = 0.124 ± 0.005 and for the corresponding χ 2 we have obtained a further improvement.

Small x behavior of parton distributions. Analytical and «frozen» coupling constants. BFKL corrections

“…The results are in good agreement with the experimental data (see contribution [33] by Paolo Bolzoni to this Proceedings).…”