Speaker
Description
Recent ALICE and ATLAS measurements have established groomed jet splitting angles as sensitive probes of jet-medium interactions in the quark-gluon plasma (QGP)~\cite{ATLAS:2022qef,ALICE:2021jid}. In particular, ATLAS observed that large-$r_g$ jets are roughly twice as suppressed as small-$r_g$ jets in central Pb+Pb collisions~\cite{ATLAS:2022qef}, suggesting stronger energy loss for wider jet substructures.
In this work, we conduct a systematic study on the substructure-dependent of jet suppression within a hybrid Pythia 8+LBT framework~\cite{Zeng:2025xxx}, where Pythia 8 generates the initial vacuum-like parton shower and the Linear Boltzmann Transport (LBT) model simulates the subsequent in-medium evolution of jet partons through elastic and inelastic interactions with the QGP.
We first present the groomed jet differential cross section, ${\rm d}^2\sigma/({\rm d}r_g\,{\rm d}p_{\rm T})$, in p+p collsions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV as the vacuum baseline for substructure-selected jet suppression. In Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV, we analyze the $R_{\mathrm{AA}}$ as a function of jet $p_{\rm T}$ for jets with different $r_g$ intervals; and analyze $R_{\rm AA}$ as a function of $r_g$ for jets with different $p_{\mathrm{T}}$ intervals. Those calculations enable a direct comparison with ATLAS data. Furthermore, we discuss different contribution -- jet energy loss, medium-induced gluon emission and medium response -- to the $R_{\mathrm{AA}} (p_{\mathrm{T}})$ and $R_{\mathrm{AA}} (r_g)$, thereby helping to disentangle the mechanisms responsible for the splitting-angle dependence of jet suppression.
