
In this talk I shall start with the double logarithmic correction to the transverse momentum broadening of high-energy parton in QCD matter. Such a double logarithmic term, averaged over the path length of the partons, can be taken as the radiative correction to the jet quenching parameter q and contributes to radiative energy loss.
Then, I shall discuss that the unintegrated quark distribution includes such a medium double log as well as Sudakov double logs. At the end, I shall talk about how such a double log is hidden in the small-x evolution of a quark-antiquark dipole described by the Balitsky-Kovchegov equation in a large nucleus.