SLIDE 1
PYTHIA (6 & 8) versus pp data at the LHC
Peter Skands (CERN)
Winter Workshop on Recent QCD Advances at the LHC, Les Houches, F
- P. Skands
QCD in PYTHIA
2
From Tevatron to LHC
Tevatron tunes appear to be “low” on LHC data Problem for “global” tunes. Poor man’s short-term solution: dedicated LHC tunes
E.g., Rick Field
Regularise cross section with p⊥0 as free parameter dˆ σ dp2
⊥
∝ α2
s(p2 ⊥)
p4
⊥
→ α2
s(p2 ⊥0 + p2 ⊥)
(p2
⊥0 + p2 ⊥)2
with energy dependence p⊥0(ECM) = pref
⊥0 ×
- ECM
Eref
CM
- Matter profile in impact-parameter space
IR Regularization Energy Scaling Multiple Parton Interactions (MPI) See, e.g., new MCnet Review: “General-purpose event generators for LHC physics”, arXiv:1101.2599