Probing Gluon Fluctuations in Nuclei with the First Energy-Dependent Measurement of Incoherent J/ψ Photoproduction in Ultraperipheral PbPb Collisions

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F25%3A10511253" target="_blank" >RIV/00216208:11320/25:10511253 - isvavai.cz</a>
Result on the web
<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=K_VbBJsRA4" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=K_VbBJsRA4</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1103/w9kp-f8xr" target="_blank" >10.1103/w9kp-f8xr</a>

Result language
angličtina
Original language name
Probing Gluon Fluctuations in Nuclei with the First Energy-Dependent Measurement of Incoherent J/ψ Photoproduction in Ultraperipheral PbPb Collisions
Original language description
Incoherent J/psi photoproduction in heavy ion ultraperipheral collisions (UPCs) provides a sensitive probe of localized, fluctuating gluonic structures within heavy nuclei. This Letter reports the first measurement of the photon-nucleon center-of-mass energy (W-gamma N) dependence of this process in PbPb UPCs at a nucleon-nucleon center-of-mass energy of 5.02 TeV, using 1.52 nb(-1) of data recorded by the CMS experiment. The measurement covers a wide W-gamma N range of approximate to 40-400 GeV, probing gluons carrying a fraction x of nucleon momentum down to an unexplored regime of 6.5 x 10(-5). Compared to baseline predictions neglecting nuclear effects, the measured cross sections exhibit significantly greater suppression at lower x. Additionally, the ratio of incoherent to coherent photoproduction is found to be constant across the probed W-gamma N and x range, disfavoring the establishment of the black disk limit. This Letter provides critical insights into the x-dependent evolution of fluctuating gluonic structures within nuclei and calls for further advancements in theoretical models incorporating nuclear shadowing and gluon saturation.
Czech name
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Czech description
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Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10300 - Physical sciences

Project
<a href="/en/project/LM2023040" target="_blank" >LM2023040: Research infrastructure for experiments at CERN</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year
2025
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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