Recent results on hard processes in p+Pb, Pb+Pb, and pp collisions from the ATLAS Experiment at the LHC

In relativistic heavy-ion collisions, a hot medium with a high density of unscreened colour charges is produced. Hard processes that are produced by parton-parton scatterings in the early stages of the collision can be used as probes of the medium since the initial state is mostly understood such that any differences from pp collisions in the final state can be attributed to interactions with the medium. The initial and final state effects are separated by comparing p+Pb and pp collisions. Recent ATLAS results on electro-weak bosons, jets, and quarkonia are discussed in both p+Pb and Pb+Pb collisions, compared to pp. Recent results on ultra–peripheral collisions by ATLAS are also shown.