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 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.1 A more exotic solution to this problem was proposed in [7].

It is shown that the contribution from double parton scattering to the inclusive double heavy meson yield is quite comparable with the usually considered mechanism of their production at the LHC energy. For some pairs of heavy flavored quarks in the final state the double parton scattering will be a dominant mode of their production.

We find out the connection between the unintegrated gluon distribution at low intrinsic transverse momenta and the inclusive spectrum of the hadrons produced in pp collision at LHC energies in the mid-rapidity region and low hadron transverse momenta. The parameters of this distribution are found from the best description of the LHC data. Its application to the analysis of ep deep inelastic scattering allows us to obtain the results which describe reasonably well the H1 and ZEUS data on the structure functions at low x. A connection between the soft processes at LHC and small x physics at HERA has been found. PACS number(s): 12.38.-t, 13.85.-t

We calculate the perturbative parts of the structure functions F c 2 and F c L for a gluon target having nonzero transverse momentum squared at order α s . The results of the double convolution (with respect to the Bjorken variable x B and the transverse momentum ) of the perturbative part and the unintegrated gluon densities are compared with HERA experimental data for F c 2 . The contribution from F c L structure function ranges 10 ÷ 30% of that of F c 2 at the kinematical range of HERA experiments.

In the framework of the k T -factorization approach, the production of prompt photons in association with a heavy (charm or beauty) quarks at high energies is studied. The consideration is based on the O(αα 2 s ) off-shell amplitudes of gluon-gluon fusion and quark-(anti)quark interaction subprocesses. The unintegrated parton densities in a proton are determined using the Kimber-Martin-Ryskin prescription. Our numerical predictions are compared with the D0 and CDF experimental data. Also we extend our results to LHC energies.