Jun 12 – 16, 2017
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Europe/Zurich timezone

Jet fragmentation in two particle correlation in Pb-Pb sqrt(sNN)=2.76 TeV

Jun 13, 2017, 3:20 PM
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Other Institutes

Nikhef Science Park 105 1098XG Amsterdam The Netherlands


Marton Vargyas (University of Jyvaskyla (FI))


The modification in jets measured in heavy-ion collisions as compared to jets measured in pp collisions is a rich source of information on the medium properties. The medium-induced modifications are typically seen more clearly at low-$p_{\rm T}$, where full jet reconstruction is difficult due to the very large background in heavy ion collisions. Two-particle correlations provide a way to study jets in the low- and intermediate-$p_{\rm T}$ regime. Jet fragmentation is observed as a peak around $(\Delta\eta, \Delta\phi)=(0,0)$ in two-particle correlations, where $\Delta\eta$ and $\Delta\phi$ are the differences in pseudorapidity and azimuthal angle, respectively, between a trigger particle and associated particles.

In this talk, we will present ALICE measurements of $I_{\rm AA}$, the jet peak yield in Pb-Pb divided by the yield from pp collisions, at $\sqrt{s_{\rm NN}} = 2.76$ TeV. From $\Delta\eta$-dependent $I_{\rm AA}$, we observe that jets with 6$<$$p_{\rm T,trig.}$$<$8 GeV/c and 8$<$$p_{\rm T,trig.}$$<$15 GeV/c show a narrowing in pseudorapidity. This effect is prominent in central collisions and for high trigger momentum while it vanishes in peripheral collisions or for low trigger momentum. From the integrated, $p_{\rm T}$-dependent $I_{\rm AA}$ we see enhancement at low-$p_{\rm T}$ in central collisions. These observations can be used to constrain energy loss models, particularly models that predict broadening of the jet by interactions with the medium.

List of tracks Charge fluctuations, correlations and balance functions

Primary authors

Marton Vargyas (University of Jyvaskyla (FI)) ALICE collaboration

Presentation materials