Impact of CMS dijets in 5.02 TeV pPb and pp collisions on EPPS16 nuclear PDFs

Understand

The CMS measurement of dijet pseudorapidity distributions in pPb versus pp collisions at 5.02 TeV provides a direct probe on nuclear gluon PDFs.

• We show that while the predicted pPb pseudorapidity distributions suffer from sizable free-proton PDF uncertainties, the ratios of the pPb and pp distributions are practically insensitive to scale and free-proton PDF choices.
• We find the CMS data on pPb to pp ratios to be in good agreement with the EPPS16 nuclear modifications.
• Using a non-quadratic extension of the Hessian PDF reweighting method, we study the impact of these data on the EPPS16 nuclear PDFs.