Hadron-Hadron collisions (2)
PDFs, FFs and as depend on 3 (arbitrary) scales (when the perturbative expansion does not include ALL orders in as ):
- Factorization (M), Renormalization (m), Fragmentation (Mf) scales.
- Single (optimal) scale: M = m = Mf = (pT/3 - 2pT), fixed by the “Principle of Minimum Sensitivity” (PMS).
- NLO predictions unstable at pT< 4 GeV/c for low s1/2 (< 60 GeV) reactions (resummed theory needed) !
Comparison to available pp,ppbar ? g,poX data:
- pp: WA70 (s1/2=24 GeV), R806 (ISR), R110, AFS, R108 ...
- Fixed target: E706 (pBe), and UA6 (pp, ppbar) ...