2020/01/28 by K. Eskola, Kari J. Eskola, Ilkka Helenius +2
Physics and Astronomy · #D meson #DGLAP #Gluon #Hessian matrix #High-Energy Particle Collisions Research #Large Hadron Collider #Meson #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Parton #Physics #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Rapidity #Scattering #hep-ph
paper · pdf · doi:10.1016/j.nuclphysa.2020.121944
4 pages, 4 figures, presented at the XXVIIIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2019), Wuhan, China
arxiv created 2020/01/28 · openalex created_date 2020/02/07 · openalex publication_date 2020/12/11 · arxiv updated 2021/02/03 · openalex updated_date 2026/08/05
We discuss the new constraints on gluon parton distribution function (PDF) in lead nucleus, derivable with the Hessian PDF reweighting method from the 5.02 TeV p+Pb measurements of dijet (CMS) and D0-meson (LHCb) nuclear modification ratios. The impact is found to be significant, placing stringent constraints in the mid- and previously unconstrained small-x regions. The CMS dijet data confirm the existence of gluon anti-shadowing and the onset of small-x shadowing, as well as reduce the gluon PDF uncertainties in the larger-x region. The gluon constraints from the LHCb D0 data, reaching down to x ∼ 10-5 and derived in a NLO perturbative QCD approach, provide a remarkable reduction of the small-x uncertainties with a strong direct evidence of gluon shadowing. Furthermore, we find a good description of the data even down to zero D0-meson transverse momentum within a purely DGLAP-based approach without a need for imposing any non-linear effects. Importantly, the constraints obtained from the dijet and D0 data are mutually fully consistent, supporting the universality of nuclear PDFs in hard-scattering processes.