Generator Validation

Use this view to look for changes between generator versions (technical validation). For each version, it can also be used as a condensed summary of the overall quality of the description of the various categories of data (physics validation).

Numbers in the tables correspond to chi2 values. To make them more physically meaningful, the MC predictions are assigned a flat 5% 'theory uncertainty', as a baseline sanity limit for the achievable theoretical accuracy with present-day MC models. A few clear cases of GIGO are excluded, but some problematic cases remain. Thus, e.g., if a calculation returns a too small cross section for a dimensionful quantity, the corresponding chi2 value will be large, even though the shape of the distribution may be well described. It could be argued how this should be treated, how much uncertainty should be allowed for each observable, whether it is reasonable to include observables that a given model is not supposed to describe, etc. These are questions that we do not believe can be meaningfully (or reliably) addressed by a fully automated site containing tens of thousands of model/observable combinations. In the end, the interpretation of the information we display is up to you, the user. Exercise care and common sense when interpreting results.

← Select generator and tune

Process Summary

incl. 5% "theory uncertainty" on all points
min best min
2.1.4_6.426 <Δ> 2.1.3e_6.426
max worst max
pp/ppbar → Jets 0.0078 -7.9 0.0043
1.4 -0.40 1.8
32 +5.1 52
pp/ppbar → W 0.29 -1.5 0.85
0.54 -0.86 1.4
0.86 -0.31 2.0

Legend: [ χ2 < 1 ] / [ 1 ≤ χ2 < 4 ] / [ 4 ≤ χ2 ]

(click on number in the table cell to see individual observables)