Vacuum-like jet fragmentation in a dense QCD medium

Understand

We study the fragmentation of a jet propagating in a dense quark-gluon plasma.

• Using a leading, double-logarithmic approximation in perturbative QCD, we compute for the first time the effects of the medium on the vacuum-like emissions.
• We show that, due to the scatterings off the plasma, the in-medium parton showers differ from the vacuum ones in two crucial aspects: their phase-space is reduced and the first emission outside the medium can violate angular ordering.
• We compute the jet fragmentation function and find results in qualitative agreement with measurements at the LHC.