the gluon collides with some internal modes. Therefore it affects the medium as an “effective” wave which accounts also for the waves emitted by other scattering centers. Beside incoherent scattering, there are processes which can be described as the refraction of the initial wave along the path of the coherent wave (see, e.g., [@8]). The Cherenkov effect is the induced coherent radiation by a set of scattering centers placed on the way of propagation of the gluon. The longitudinal components of their polarization vector are important. That is why the forward scattering amplitude plays such a crucial role in formation of the refractive index. At low energies its excess over 1 is related to the resonance peaks as dictated by the Breit-Wigner shapes of the amplitudes. In experiment, usual resonances are formed during the color neutralization process. The resonant structure can reveal itself in the virtual states as well. However, only those gluons whose energies are within the left-wing resonance region of $n>1$ give rise also to the collective Cherenkov effect proportional to $\Delta n$. At high energies these excitations should lead to Cherenkov jets. In both energy regions the coherent Cherenkov emission proceeds at angles determined by Eq. (\[cos\]) 