Energy dependent nuclear suppression from gluon saturation in exclusive vector meson production
Heikki Mäntysaari, Farid Salazar, Björn Schenke
Abstract
We calculate exclusive <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi mathvariant="normal">J</a:mi><a:mo>/</a:mo><a:mi>ψ</a:mi></a:math> photoproduction at high energies in the color glass condensate approach. The results are compared to the center-of-mass energy dependent <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mi>γ</d:mi><d:mo>+</d:mo><d:mi>A</d:mi><d:mo stretchy="false">→</d:mo><d:mi mathvariant="normal">J</d:mi><d:mo>/</d:mo><d:mi>ψ</d:mi><d:mo>+</d:mo><d:mi>A</d:mi></d:math> cross sections extracted from measurements in ultraperipheral heavy ion collisions at RHIC and LHC. We predict strong saturation-driven nuclear suppression at high energies, while LHC data prefer even stronger suppression. We explore effects of nucleon shaped fluctuations and show that the most recent measurement of the <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mo stretchy="false">|</h:mo><h:mi>t</h:mi><h:mo stretchy="false">|</h:mo></h:math>-differential incoherent <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:mrow><l:mi mathvariant="normal">J</l:mi><l:mo>/</l:mo><l:mi>ψ</l:mi></l:mrow></l:math> cross section prefers large event-by-event fluctuations of the nucleon substructure in heavy nuclei, comparable to that found for a free proton. Published by the American Physical Society 2024