Hard QCD probes. Motivation (I)

• Hard probes: High-pT, jets, direct , heavy-quarks (D, B), ...

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

• Closest experimental probes to underlying QCD (q,g) degrees of freedom.

• [2] Direct probes of partonic phase(s)  Sensitive to QCD medium properties: