\nu }
{EE_R^2}\cdot \frac {E_R-E}{(E-E_R)^2+\Gamma _R^2/4},   \label{liq}$$ where $\alpha $ denotes the colour polarizability of the colour-neutral medium. The value $\nu $ obtained from this expression is almost twice lower than given above. It does not change the qualitative conclusions about the dense medium (for more details see [@6; @7]).

High-energy rings.
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At much higher energies one can expect better alignement of the momenta of initial partons. This would favour the direct observation of emitted by them rings in non-trigger experiments. The first cosmic ray event [@23] with ring structure gives some hope that at LHC energies the initial partons are really more aligned and this effect can be found. The possible additional signature would be the enlarged transverse momenta of particles within the ring.

[**Prediction 3**]{}. The very high energy forward moving partons can emit high energy Cherenkov gluons producing jets.

[**Proposal 3**]{}. Plot the pseudorapidity distribution of dense groups of particles in individual events (now again with collision axis chosen as $z$-axis) and look for maxima at angles determined by Eq. (\[cos\]).

Gluons with such energy are not abundant at RHIC but they will become available at LHC. Namely such gluons were discussed in [@1; @2] in 