Relevance of baseline hard p+p spectra for nucleus-nucleus and 
proton+nucleus physics at high pT

David d'Enterria, Nevis Labs. Columbia University

I will discuss the importance of having a concurrent and precise 
measurement of baseline high-pT spectra in p+p collisions at the same 
center-of-mass energies as the A+A, p,d+A data in order to correctly 
interpret the QCD medium phenonema in the hard regime. Four illustrative 
cases will be presented and discussed:
(i) p+p --> pi+X at sqrt(s)=17.3 GeV: Is high pT A+A hadroproduction at 
SPS enhanced or suppressed ?,
(ii) p+p --> pi+X at sqrt(s) = 62.4 GeV: How accurate is our current 
ISR-averaged p+p reference ?,
(iii) p+p --> h+X at sqrt(s) = 200 GeV at forward rapidities versus 
pQCD:  Is there truly suppresssion in d+Au collisions at eta=3.2 ?,
(iv) p+p --> gamma+X at sqrt(s) = 200 GeV: Is there a way to disentangle 
suppressed (quenched jet fragmentation) prompt photons from enhanced 
(thermal) photons in Au+Au collisions at RHIC ?