Hard QCD probes in HI collisions

• Early production (~1/pT~ 0.1 fm/c) in parton-parton scatterings with large Q2

• Direct probes of partonic phases  Sensitive to hot/dense medium effects: parton energy loss (“jet quenching”), color screening (“onia” suppression).

• Probes: High-pT (jets, prompt ), heavy-flavor (D, B, J/)

• Direct comparison to baseline "vacuum" (pp) data via “binary scaling”:

• AB = total # of binary inelastic NN colls.

• Elementary processes calculable via pQCD (Factorization theorem):

Notes: