Energy-energy correlators in jets across collision systems and parton flavors

TL;DR

The study investigates jet evolution using the energy-energy correlator $\Sigma_{\rm EEC}(R_{\rm L})$ across collision systems and parton flavors. It presents three ALICE measurements: (i) a finalized pp EEC with a clear $p_{\rm T}^{\rm ch\ jet}$-dependent peak and a universal $\langle p_{\rm T}^{\rm ch\ jet}\rangle R_{\rm L}$ scaling; (ii) the first EEC measurement in $D^0$-tagged jets in pp, revealing mass-related dead-cone suppression and a partial alignment with hadronization-model predictions; (iii) the inaugural EECs in inclusive jets in p--Pb, showing modifications relative to pp and universal behavior under scaling, with current models only qualitatively capturing the trends. These results establish $\Sigma_{\rm EEC}$ as a sensitive probe of perturbative vs non-perturbative jet dynamics, flavor-dependent radiation, and cold nuclear matter effects, informing hadronization modeling and the interpretation of jet evolution in nuclear environments.

Abstract

The two-point energy-energy correlator (EEC) is a novel jet substructure observable probing the correlation of energy flow within jets. In these proceedings, three EEC measurements performed by the ALICE Collaboration are reported. First is a finalized measurement in proton-proton collisions, where the angular dependence of the EEC cross-section shows a separation of the perturbative and non-perturbative regimes. The first EEC measurement is reported in heavy-flavor jets, tagged via a fully-reconstructed D$^0$ meson. Here, comparison to inclusive pp jets provides insights into the flavor dynamics of QCD fragmentation and hadronization. Finally, the first measurement of EECs in p-Pb collisions is presented. By comparing the results to pp, modifications in jet evolution caused by the presence of a cold nuclear medium can be studied.

Figures (9)

• Figure 1: EEC in pp collisions in three $p_{\rm T}^{\rm ch\> jet}$ ranges: 20–40, 40–60, and 60–80 GeV/$c$wfEECpp. A clear $p_{\rm T}^{\rm ch\> jet}$ dependence is seen in the EEC peak, with the distribution shifting to smaller angles as $p_{\rm T}^{\rm ch\> jet}$ increases.
• Figure 2: EEC rescaled as a function of $\langle p_{\rm T}^{\rm ch\> jet}\rangle R_{\rm L}$, showing the universality of the EEC transition region wfEECpp.
• Figure 3: Measurement of EECs in D$^0$-tagged jets in pp collisions at $\sqrt{s}$=13 TeemV. The left panel shows results for 10--15 GeemV/$c$ jets, and the right panels shows 15--30 GeemV/$c$ jets. The D$^0$-tagged jet EEC (red) is compared to inclusive jets (blue), PYTHIA (solid lines), and a pQCD calculation (shaded region).
• Figure 4: EECs as a function of $R_{\rm L}$ in D$^0$-tagged jets in data and four event generators. The left panel shows results for 10--15 GeemV/$c$ jets, and the right panels shows 15--30 GeemV/$c$ jets. The D$^0$-tagged jet EEC (red) is compared to inclusive jets (blue).
• Figure 5: EECs for jets in p--Pb collisions in three $p_{\rm T}^{\rm ch\> jet}$ intervals.