CERN Accelerating science

ATLAS Note
Report number	ATL-PHYS-PROC-2024-109
Title	Recent ATLAS results relevant for PDFs at low and high x, saturation in both $pp$ and HI collisions
Author(s)	Mondal, Santu (Czech Technical University in Prague (CZ))
Corporate Author(s)	The ATLAS collaboration
Collaboration	ATLAS Collaboration
Publication	2024
Imprint	21 Nov 2024
Number of pages	8
In:	Diffraction and Low-x 2024, Trabia, Palermo, Italy, 8 - 14 Sep 2024
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Free keywords	ATLAS Detector ; nuclear parton distribution functions (nPDFs) ; top-quark pair production (tt̄) ; proton-lead (p+Pb) collisions ; ultra-peripheral collisions (UPCs) ; TOP ; HEAVYIONS
Abstract	This proceedings summarises the results of three major studies on nuclear parton distribution functions (nPDFs) from high-energy collisions at the CERN Large Hadron Collider (LHC). The first study examines top quark pair production in $p$ + $\text{Pb}$ collisions, investigating nPDF modifications at high Bjorken $x$. The second study analyses the centrality dependence of dijet yields in $p$ + $\text{Pb}$ collisions at $\sqrt{s_{NN}} = 8.16 \, \text{TeV} $, revealing scaling behaviour with Bjorken $x $. The final study presents photon-nuclear production of dijets in ultraperipheral $\text{Pb} + \text{Pb}$ collisions at $ \sqrt{s_{NN}} = 5.02 \, \text{TeV}$, providing insights into low-$x$ gluon distributions. Collectively, these results enhance the understanding of nPDFs and lay a foundation for future investigations into photonuclear interactions and gluon saturation phenomena.