Beauty production in two-photon interactions at LEP2: $k_T$-factorization versus data

Inclusive beauty quark production in photon-photon collisions at CERN LEP2 is considered in the framework of the $k_T$-factorization approach. Both direct and resolved photon contributions are taken into account. The unintegrated gluon distributions in a photon are either obtained from the full Catani–Ciafoloni–Fioyani–Marchesini (CCFM) evolution equation or from the Kimber-Martin-Ryskin prescription. The predicted beauty cross section reasonably agrees with the recent experimental data taken by the ALEPH collaboration. We argue that theoretical and experimental studies of the azimuthal correlations in heavy quark production at high energies can serve as a crucial probe of the unintegrated gluon densities.