We present a unique signal of jet-induced medium excitations: the enhancement of baryon-tomeson ratios around the quenched jets. To illustrate this, we study the jet-particle correlations and the (∆η, ∆φ) distributions of jet-induced identified particles with respect to the jet direction in Pb+Pb collisions at the LHC via a multi-phase transport model. We find a strong enhancement of baryon-to-meson ratios around the triggered jets in Pb+Pb collisions relative to p+p collisions. The enhancement is more pronounced in more central collisions due to larger jet quenching effect, and is strongest at intermediate pT region as a result of the coalescence of jet-excited medium partons. Since the lost energy from jets can flow to large angles, jet-triggered baryon-to-meson ratios are more enhanced for larger relative distance ∆r from the jet axis. We argue that the experimental confirmation of the enhancement of jet-induced baryon-to-meson ratios around the jets will provide an unambiguous evidence for the medium response to jet quenching in heavy-ion collisions.

The overall transverse momentum balance and the redistribution of the lost energy from hard jets for asymmetric dijet events in PbPb collisions at 2.76A TeV at the LHC is studied within a multiphase transport (AMPT) model. A detailed analysis is performed for the projected transverse momentum / p || T contributed from the final charged hadrons carrying different transverse momenta and emitted from different angular directions. We find that the transverse momentum projection / p || T in the leading jet direction is mainly contributed by hard hadrons (p T > 8.0 GeV/c) in both peripheral and central PbPb collisions, while the opposite direction in central collisions is dominated by soft hadrons (p T = 0.5-2.0 GeV/c). The study of in-cone and out-of-cone contributions to / p || T shows that these soft hadrons are mostly emitted at large angles away from the dijet axis. Our AMPT calculation is in qualitative agreement with the CMS measurements and the primary mechanism for the energy transported to large angles in the AMPT model is the elastic scattering at the partonic stage. Future studies including also inelastic processes should be helpful in understanding the overestimation of the magnitudes of in-cone and out-of-cone imbalances from our AMPT calculations, and shed light on different roles played by radiative and collisional processes in the redistribution of the lost energy from hard jets.

Jet-medium interaction involves two important effects: jet energy loss and medium response. The search for jet-induced medium excitations is one of the hot topics in jet quenching study in relativistic nuclear collisions. In this work, we perform a systematic study on how the lost energy from hard jets evolves with the bulk medium and redistributes in the final state of heavy-ion collisions via a multi-phase transport model. In particular, the ($$\Delta \eta , \Delta \phi $$ Δ η , Δ ϕ ) distribution of charged particles with respect to the jet axis and jet shape function are studied for various Pb + Pb collision centralities and for different transverse momentum intervals of charged particles. Our numerical result shows a strong enhancement of soft particles at large angles for Pb + Pb collisions relative to p + p collisions at the LHC, qualitatively consistent with recent CMS data. This indicates that a significant fraction of the lost energy from hard jets is carried by soft particles at large angles away from the jet axis.

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