Cherenkov glue in opaque nuclear medium

The spectrum of Cherenkov gluons is calculated within the framework of in-medium QCD. It is compared with experimental data on the double-humped structure around the away-side jet obtained in the experiments STAR and PHENIX at RHIC. The values of the real and imaginary parts of the permittivity of the medium created in ultrarelativistic nuclear collisions are obtained from these fits. It is shown that accounting for an additional smearing of transverse momenta of Cherenkov gluons in the medium allows to provide a very good description of the experimental data.