correlations studied at RHIC [@pr] are its less direct indications although they have the ring-like structure themselves.

Thus we can ascribe two contributions to the away-side hadrons associated with the companion jet: one from jet fragmentation and the other from Cherenkov gluons. The hadrons from jet fragmentation are smoothly distributed within the phase space volume. In distinction, the one-dimensional distribution along the ring diameter of the away-side hadrons created by Cherenkov gluons must possess two peaks.

Let us note that the azimuthal angles $\Delta \phi $ in Fig. 1 are considered as the polar angles $\theta $ in our treatment because the role of $z$-axis is now played by the jet axis in place of the axis of collisions. The ring is placed in the plane perpendicular to the jet axis. The two maxima in the right-hand side of Fig. 1 appear due to its projection on the diameter. The distance between them is exactly equal to the diameter of the ring.

From the distance between the peaks defined in angular ($\theta =D$ in PHENIX notation) variables in Fig. 1 one gets according to Eq. (\[cos\]) the nuclear refractive index. Its value is found to be quite large $n=3$ compared 