Event-by-event fluctuations in the medium-induced jet evolution

Abstract

We develop the event-by-event picture of the gluon distribution produced via medium-induced gluon branching by an energetic jet which propagates through a dense QCD medium. A typical event is characterized by the production of a large number of soft gluons which propagate at large angles with respect to the jet axis and which collectively carry a substantial amount of energy. By explicitly computing 2-gluon correlations, we demonstrate the existence of large event-by-event fluctuations, which reflect the stochastic nature of the branching process. For the two quantities that we have investigated -- the energy loss at large angles and the soft gluon multiplicity --, the dispersion is parametrically as large as the respective expectation value. We identify interesting scaling laws, which suggest that the multiplicity distribution should exhibit KNO (Koba-Nielsen-Olesen) scaling. A similar scaling is known to hold for a jet branching in the vacuum, but the medium-induced distribution is found to be considerably broader. We predict that event-by-event measurements of the di-jet asymmetry in Pb+Pb collisions at the LHC should observe large fluctuations in the number of soft hadrons propagating at large angles and also in the total energy carried by these hadrons.

39 pages, 7 figures

References in corpus (9)

• Measurement of jet fragmentation in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV
• Antiangular Ordering of Gluon Radiation in QCD Media
• Measurement of inclusive jet charged-particle fragmentation functions in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV with the ATLAS detector
• Jet Structure in Heavy Ion Collisions
• Picturing perturbative parton cascades in QCD matter
• Angular structure of the in-medium QCD cascade
• Medium-induced gluon radiation and colour decoherence beyond the soft approximation
• Angular distribution of medium-induced QCD cascades
• Energy flow along the medium-induced parton cascade

Cited by in corpus (8)

• Deciphering the $z_g$ distribution in ultrarelativistic heavy ion collisions
• Resolution Effects in the Hybrid Strong/Weak Coupling Model
• Measurement of angular and momentum distributions of charged particles within and around jets in Pb+Pb and $pp$ collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ATLAS detector
• In-medium modification of dijets in PbPb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV
• Strong- vs. weak-coupling pictures of jet quenching: a dry run using QED
• In-medium gluon radiation spectrum with all-order resummation of multiple scatterings in longitudinally evolving media
• Multi-particle correlations and KNO scaling in the medium-induced jet evolution
• Event-by-event picture for the medium-induced jet evolution