Speaker
Description
Jet quenching provides a sensitive probe of the transport properties and microscopic structure of the quark-gluon plasma (QGP). In this work, we use the Linear Boltzmann Transport (LBT) model to study jet-medium interactions from two complementary perspectives: photon-tagged jet observables in different collision systems and multi-point energy correlators inside jets.
The first part focuses on photon-tagged jet production and modification. We validate the LBT calculation with CMS measurements of photon-tagged jets in Pb+Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV, including the momentum imbalance $x_{J\gamma}$, the associated-jet yield modification $I_{\rm AA}^{\rm jet}$, and the azimuthal correlation $\Delta\phi_{J\gamma}$. The associated-jet transverse-momentum spectrum and the parton-level $\Delta p_T$ are used as model diagnostics to connect the observed imbalance and yield suppression to jet energy loss and medium response. With the same transport setup, we then provide predictions for photon-tagged jet observables in O+O collisions at $\sqrt{s_{\rm NN}}=5.36$ TeV. The results show that O+O exhibits a visible but weaker pattern of jet energy loss and yield modification than Pb+Pb. We further study the jet profile $\rho(r)$ and the energy-energy correlator (EEC) of photon-tagged jets to resolve the internal angular redistribution of jet energy. The EEC ratio shows small-angle suppression and large-angle enhancement, with a weaker modification in O+O than in Pb+Pb. The crossing angle of the EEC ratio decreases with increasing photon transverse momentum, consistent with the expectation that the relevant angular scale is tied to the hard jet scale.
The second part studies the three-point energy correlator (E3C) as a more differential probe of jet substructure modification. After validating the calculation against the two-point EEC results, we examine E3C edge distributions and the full $(\xi,\phi)$ shape space in both vacuum and medium-modified jets. The AA/pp ratio of the E3C shows that the medium modification is not uniform over the three-particle geometry, but is enhanced in configurations sensitive to broad-angle correlations and medium response. To identify the origin of this structure, we decompose the partonic E3C into contributions from shower partons, medium-induced radiated gluons, and jet-induced medium response. This decomposition shows that radiation-related and medium-response-related triplets populate different regions of the E3C shape space, providing a way to separate perturbative shower modification from wake-like medium response.
Together, these studies use the same LBT framework to connect conventional photon-tagged jet observables with energy-correlator-based jet substructure measurements. The photon-tagged jet analysis constrains the overall energy-loss phenomenology and extends it to O+O predictions, while the EEC and E3C analyses probe the angular pattern and microscopic origin of the medium modification inside jets.
| Academic Status | I am a master student |
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