Study · Topic 3
The global-fitting machine — from measurements to PDFs
The engineering: parametrizations, sum-rule algebra, FK tables, and the χ² done right. Each section below is a full chapter: complete mathematical treatment, derivations, diagrams, and worked examples.
3.1The inverse problem and parametrizationsLH toy, MSHT20 Chebyshev form in full, NNPDF nets, grids — with the MSHT20 basis written out.
3.2Sum rules analytically: the Euler-Beta machineryEvery normalization integral derived — the exact algebra our MSHT20 port runs.
3.3FK tables and the theory pipelineFrom PineAPPL grids through EKO to the linear/quadratic contractions fits evaluate.
3.4The χ², correlated systematics, and t0Covariance anatomy, nuisance-parameter equivalence derived, the d'Agostini bias and its fix.