The EPPS16 nuclear PDFs

TL;DR

The EPPS16 paper presents a comprehensive NLO nuclear PDFs analysis incorporating LHC p-Pb data and updated theoretical frameworks, reducing bias and supporting collinear factorization in heavy-ion collisions.

Contribution

It introduces the first NLO nuclear PDFs analysis using LHC p-Pb data with a flexible flavor-dependent modification approach, improving upon previous models.

Findings

All data well reproduced by the model

Supports collinear factorization in heavy-ion collisions

Uncertainties remain large for individual flavors

Abstract

We report on EPPS16 - the first analysis of NLO nuclear PDFs where LHC p-Pb data (Z, W, dijets) have been directly used as a constraint. In comparison to our previous fit EPS09, also data from neutrino-nucleus deeply-inelastic scattering and pion-nucleus Drell-Yan process are now included. Much of the theory framework has also been updated from EPS09, including a consistent treatment of heavy quarks in deeply-inelastic scattering. However, the most notable change is that we no longer assume flavour-blind nuclear modifications for valence and sea quarks. This significantly reduces the theoretical bias. All the analysed data are well reproduced and the analysis thereby supports the validity of collinear factorization in high-energy collisions involving heavy nuclei. However, flavour by flavour, the uncertainties are still rather large.