Collisional energy losses of heavy quarks in relativistic nuclear   collisions at energies available at the BNL Relativistic Heavy Ion Collider
  We investigate the energy losses of $b$ and $c$ quarks at hard collisions with gluons and light quarks in quark-gluon plasma produced in central $Au + Au$ collisions at RHIC energy($\sqrt{s_{NN}} = 200$ GeV). As the coupling constant at hard collision in the perturbative QCD is limited by Landau pole at momenta $Q^{2} = \Lambda^{2}$, we use the analytic models of QCD, where the Landau pole is absent. We calculate the energy losses of $b$ and $c$ quarks in analytic model of QCD at $Q^{2} \ge \Lambda^{2}$. At calculations we use the effective quasiparticle model. We use at calculations of total nuclear modification factor $R_{AA}^{b+c}$ the fragmentation of $b$ and $c$ quarks into heavy hadrons with accounting theirs energy losses. We show that this factor gives the considerably suppression of heavy $B$ and $D$ mesons in the region of middle meanings of $p_{\perp}$. The experimental data \cite{2} show, that nonphotonic electrons have the analogous suppression in the same region of $p_{\perp}$. 
Yu.A. Tarasov
hep-ph nucl-th