EPPS16 - First nuclear PDFs to include LHC data

TL;DR

The EPPS16 global analysis of nuclear PDFs incorporates LHC data for the first time, improving flavor-dependent nuclear modification constraints and supporting collinear factorization in nuclear collisions.

Contribution

First inclusion of LHC dijet and heavy gauge boson data in a global nPDF fit, enabling flavor-dependent nuclear modifications and validating collinear factorization.

Findings

LHC data significantly constrain gluon nuclear modifications.

Flavor dependence of valence and sea quark modifications is now accessible.

No tension found among different data sets, supporting universality of nPDFs.

Abstract

We present results of our recent EPPS16 global analysis of NLO nuclear parton distribution functions (nPDFs). For the first time, dijet and heavy gauge boson production data from LHC proton-lead collisions have been included in a global fit. Especially, the CMS dijets play an important role in constraining the nuclear effects in gluon distributions. With the inclusion of also neutrino-nucleus deeply-inelastic scattering and pion-nucleus Drell-Yan data and a proper treatment of isospin-corrected data, we were able to free the flavor dependence of the valence and sea quark nuclear modifications for the first time. This gives us less biased, yet larger, flavor by flavor uncertainty estimates. The EPPS16 analysis indicates no tension between the data sets used, which supports the validity of collinear factorization and universal nPDFs for nuclear hard-collision processes in the kinematical range studied.