Dijet hadrochemistry: tomography of jet-induced medium excitation and diffusion wake

Abstract

Energetic partons traversing the quark-gluon plasma in relativistic heavy-ion collisions induce a medium response that modifies the production of associated hadrons, whose chemical composition provides a sensitive probe of this response. We study jet-associated hadrochemistry using the coupled linear Boltzmann transport and hydrodynamics model with a hybrid hadronization scheme that combines Cooper--Frye particlization, quark coalescence and string fragmentation. For inclusive charged jets in $p+p$ and 0--10\% central Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$~TeV, the calculated in-cone $K/\pi$ and $p/\pi$ ratios are enhanced in Pb+Pb relative to $p+p$ collisions, consistent with preliminary ALICE measurements, with coalescence between shower and thermal partons providing a substantial contribution. Extending the analysis to dijet events, we predict that both ratios are enhanced around the leading and subleading jets, more strongly around the subleading jet and more pronounced for larger radial size. After mixed-event acceptance correction and sideband background subtraction, the yields of associated pions, kaons and protons all become negative near $|\Delta \varphi |\simeq \pi /2$, signaling a depletion caused by the diffusion wake. The $K/\pi$ and $p/\pi$ ratios of these deficits remain finite and exceed the $p+p$ values around the jet peaks, indicating that the missing hadrons originate from jet-excited medium. These results establish dijet hadrochemistry as an experimentally accessible tomographic probe of jet-induced medium excitation and the diffusion wake.

Comments: Main text: 8 pages, 5 figures. Supplemental Material: 2 pages, 3 figures