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

Relativistic heavy-ion collision events containing rare final states involving high transverse momentum objects provide in situ probe which allow characterization of the hot, dense QCD matter formed in these collisions. When compared with comparable yields in proton-lead and proton-proton collisions, hadronic jets and quarkonia (both for charm and bottom quarks) are observed to have significantly modified yields and fragmentation properties in lead-lead collisions. Details of these modifications carry information about the interaction of partons with the medium as well as the properties of the medium. By comparison, yields of photons and massive electroweak bosons in lead-lead and proton-lead collisions are found to be essentially unmodified compared to expectations, including isospin effects. With increasing integrated luminosities, these measurements can be used to measure nuclear parton distribution functions and other geometric aspects of the initial state. This talk will present the most recent results on quarkonia, jet, heavy flavor and electroweak boson production, measured in Pb+Pb and p+Pb collisions. The talk covers also includes recent results on gamma-gamma and photonuclear processes studied in ultraperipheral collisions. This is a growing program, complementary to inelastic heavy ion collisions, which produces hard probes via electromagnetically.