NEW TESTS FOR THE kT–FACTORIZATION: HEAVY QUARK PRODUCTION AT HERA

Abstract

The beauty production at high energies is a subject of intensive study from both theoretical and experimental points of view. Recently H1 and ZEUS collaborations have reported important data [l-31 on the beauty photoproduction at HERA which refer to small values of the Bjorken variable z. These data are in a reasonable agreement with NLO QCD predictions or somewhat higher. Some disagreement is observed [3] mainly at small decay muon and/or associated jet transverse momenta. But the large excess of the first measurements over NLO QCD, reported by the H1 collaboration 141, is not confirmed. The present note is summary of the results [5] obtained in the so-called IcT-factorization [6, 71 (or semi-hard [8, 91) approach of QCD. We investigated a number of different photoproduction rates and make comparisons with the recent H1 and ZEUS data [l-31. Both direct (yg + bb) and resolved photon contributions (gg 4 bb) are taken into account. Our analysis covers also both inclusive and dijet associated b-quark production. In last case special attention is put on the z:bs variable. In the numerical analysis we test different unintegrated gluon distributions (UGD).