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Correlations and flavors in jets in ALICE

Research paper by Filip Krizek

Indexed on: 07 Sep '15Published on: 07 Sep '15Published in: High Energy Physics - Experiment



Abstract

We report on the measurement of hadron composition in charged jets in pp at $\sqrt{s}=7$ TeV and show the first data on particle type dependent jet fragmentation at the LHC. Further, we present $(\Lambda+\bar{\Lambda})/2$K$^{0}_{\mathrm{S}}$ ratios measured in charged jets in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV and in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV. While the ratio of the inclusive $p_{\mathrm{T}}$ spectra of $\Lambda$ and K$^{0}_{\mathrm{S}}$ exhibits centrality dependent enhancement both in Pb-Pb and p-Pb system, the $(\Lambda+\bar{\Lambda})/2$K$^{0}_{\mathrm{S}}$ ratio measured in charged jets reveals that jet fragmentation does not contribute to the observed baryon anomaly. Finally, we discuss the measurement of semi-inclusive $p_{\mathrm{T}}$ spectra of charged jets that recoil from a high-$p_{\mathrm{T}}$ hadron trigger in Pb-Pb and pp collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV and $\sqrt{s} = 7$ TeV, respectively. The jet yield uncorrelated with the trigger hadron is removed at the event-ensemble level without introducing a bias on the jet population which is therefore infrared and collinear safe. The recoil jet yield in central Pb-Pb is found to be suppressed w.r.t. that from pp PYTHIA reference. On the other hand, there is no sign of intra-jet broadening even for anti-$k_{\mathrm{T}}$ jets with a resolution parameter as large as $R=0.5$.