"Conventional" nuclear effects (1) : Cronin enhancement

• Increased high-pT production in pA, AA collisions: RAB >1 (for pT > 2 GeV/c)

• Initial-state multiple (soft & semi-hard) parton

• interactions (before hard scattering): kT broadening

• [e.g.at ÖsNN = 200 GeV, broadening ~ 0.4 GeV 2/coll. additional to

• intrinsic proton kT2~2.0 GeV 2 ]

• Exactly the opposite trend is observed at RHIC !