Correlations and Jets in Heavy-Ion Collisions

Interactions of jets with the medium produced in heavy-ion collisions can provide important insight into the properties of the medium. This can be explored via particle correlations. Two-particle correlations with high $p_{T}$ triggers have shown modified structures on both the near-side and away-side. The near-side shows a ``ridge'', a structure that is correlated in azimuth but exhibits a long range structure in pseudo-rapidity. The ridge could be explained by partons bent in chromo-magnetic fields, couplings with longitudinal flow, or other mechanisms. The away-side shows a broadened and even double peaked structure in azimuth. Conical emission from Mach-cone shock waves or \v{C}eronkov gluon radiation along with other physics mechanisms have been suggested to explain this modification. Three-particle correlations and correlations with identified particles have been employed to provide further insight into both the near-side and away-side modifications. This talk will review medium responses to jet probes studied with 2-particle and 3-particle correlations.