Hidalgo Duque, CarlosLlanes Estrada, Felipe José2023-06-182023-06-182015-05-100217-751X10.1142/S0217751X15500670https://hdl.handle.net/20.500.14352/24044© 2015 World Scientific Publishing. We thank J. Liao from Indiana University for pointing to us that the literature lacks assessments of ^q in the hadronic phase, which this work attempts to supply, and for reading the first manuscript, as well as M. Benzke, N. Brambilla, A. Gomez Nicola, A. Sabio-Vera and J. Torres-Rincon for useful comments and references. Financial support by Spanish Grants FPA2011-27853-C02-01 and FIS2011-28853-C02-02. C. Hidalgo-Duque thanks the support of the JAE-CSIC Program.We study the collisional aspects of jet quenching in a high-energy nuclear collision, especially in the final state pion gas. The jet has a large energy, and acquires momentum transverse to its axis more effectively by multiple soft collisions than by few hard scatterings (as known from analogous systems such as J/ψ production at Hera). Such regime of large E and small momentum transfer corresponds to Regge kinematics and is characteristically dominated by the pomeron. From this insight we estimate the jet quenching parameter in the hadron medium (largely a pion gas) at the end of the collision, which is naturally small and increases with temperature in line with the gas density and compare it to the jet quenching parameter obtained within the quark-gluon plasma (QGP) phase in widely known perturbative approximations. The physics in the quark-gluon plasma/liquid phase is less obvious, and here we revisit a couple of simple estimates that suggest indeed that the pomeron-mediated interactions are very relevant and should be included in analysis of the jet quenching parameter. Finally, since the occasional hard collisions produce features characteristic of a Lèvy flight in the q^2_⊥ plane perpendicular to the jet axis, we suggest one- and two-particle q_⊥ to correlations as interesting experimental probes sensitive to the nature (softness versus hardness) of the interactions of a jet inside the QGP.engjournal articlehttp://dx.doi.org/10.1142/S0217751X15500670http://www.worldscientific.com/open access53Radiative energy-lossQcdPomeronTemperatureScatteringCollisionsDiffusionLatticeGluonsHeraFísica (Física)22 Física