Low-$x$ parton densities accounting for absorptive effects and exclusive $J/\psi$ and ${\rm Y}$ data from the LHC

Abstract

Based on the combined Deep-Inelastic Scattering (DIS) data from HERA and the exclusive $J/\psi$ and ${\rm Y}$ cross sections measured at the LHC, we investigate the role of absorptive corrections on the low-$x$ behaviour of parton distribution functions (PDFs) at low and moderate scales. Using $\text{xFitter}$, we study the impact of these data and of non-linear evolution on PDFs at next-to-leading order (NLO) and through the NNLO${}^{\ast }$ method introduced in a previous work. Finally, we determine the effective size of proton hot spots within this framework and discuss the implications of our results for future global PDF determinations.

arXiv comment21 pages, 11 figures, 6 tables