Central rapidity densities of charged particles at RHIC and LHC

Predictions on central rapidity densities of charged particles at energies ofthe Relativistic Heavy Ion Collider and the Large Hadron Collider, for centralcollisions between the largest nuclei that will be available at theseaccelerators, are reviewed. Differences among the results of the existingmodels are discussed in relation with their underlying physical basis and withthe possibilities to discriminate them

A-dependence of heavy flavour production in QCD

We calculate the A-dependence of charm and beauty production cross sections on nuclear targets taking into account the difference of quark and gluon distributions in free nucleons and in nucleus. At comparatively low energies, if \sigma \sim A^{\alpha}, the value of \alpha is slightly higher than unity. With the growth of the initial energy the value of \alpha decreases and becomes smaller than unity. We also calculate the values of \alpha for different Feynman-x of the produced Q\overline{Q} pair and obtain that they decrease significantly in the beam fragmentation region