Multiplicity Distributions for Jet Parton Showers in the Medium

Nicolas Borghini

The jet-quenching explanation of the suppression of high-pT hadron production at RHIC implies that jet multiplicity distributions and jet-like particle correlations in heavy-ion collisions at RHIC and LHC differ strongly from those observed at e+e- or hadron colliders. We present a framework for describing the medium-induced modification, which has a direct interpretation in terms of a probabilistic medium-modified parton shower, treating leading and subleading partons on an equal footing. We show that the strong suppression of single inclusive hadron spectra measured in Au-Au collisions at RHIC implies a characteristic distortion of the single inclusive distribution of soft partons inside the jet. We determine, as a function of jet energy, to what extent the soft fragments within a jet can be measured above some momentum cut. Recent developments obtained within the formalism will be discussed.