Parton distributions for the LHC Run II

TL;DR

The paper introduces NNPDF3.0, a validated set of parton distribution functions for LHC analyses, incorporating diverse datasets and theoretical corrections, with implications for Higgs production at 13 TeV.

Contribution

It presents a new methodology for PDF determination validated by closure tests, enabling consistent analysis across different datasets and perturbative orders.

Findings

Validated PDFs reproduce known distributions accurately.

Inclusion of latest LHC data refines PDF uncertainties.

Implications for Higgs cross-section predictions at 13 TeV.

Abstract

We present NNPDF3.0, the first set of parton distribution functions (PDFs) determined with a methodology validated by a closure test. NNPDF3.0 uses a global dataset including HERA-II deep-inelastic inclusive cross-sections, the combined HERA charm data, jet production from ATLAS and CMS, vector boson rapidity and transverse momentum distributions from ATLAS, CMS and LHCb, W+c data from CMS and top quark pair production total cross sections from ATLAS and CMS. Results are based on LO, NLO and NNLO QCD theory and also include electroweak corrections. To validate our methodology, we show that PDFs determined from pseudo-data generated from a known underlying law correctly reproduce the statistical distributions expected on the basis of the assumed experimental uncertainties. This closure test ensures that our methodological uncertainties are negligible in comparison to the generic theoretical and experimental uncertainties of PDF determination. This enables us to determine with confidence PDFs at different perturbative orders and using a variety of experimental datasets ranging from HERA-only up to a global set including the latest LHC results, all using precisely the same validated methodology. We explore some of the phenomenological implications of our results for the upcoming 13 TeV Run of the LHC, in particular for Higgs production cross-sections.