Incoherent J/ψ 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_{γN}) 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_{γN} range of ≈40-400  GeV, probing gluons carrying a fraction x of nucleon momentum down to an unexplored regime of 6.5×10^{-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_{γN} 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.

Probing Gluon Fluctuations in Nuclei with the First Energy-Dependent Measurement of Incoherent J/Psi Photoproduction in Ultraperipheral PbPb Collisions / Chekhovsky, V., Hayrapetyan, A., Makarenko, V., Tumasyan, A., Adam, W., Andrejkovic, J. W., Benato, L., Bergauer, T., Chatterjee, S., Damanakis, K., Dragicevic, M., Hussain, P. S., Jeitler, M., Krammer, N., Li, A., Liko, D., Mikulec, I., Schieck, J., Schöfbeck, R., Schwarz, D., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - ELETTRONICO. - 135:(2025), pp. 0-0. [10.1103/w9kp-f8xr]

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

Ciulli, V.;D'Alessandro, R.;Focardi, E.;Latino, G.;Lenzi, P.;Calandri, A.;
2025

Abstract

Incoherent J/ψ 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_{γN}) 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_{γN} range of ≈40-400  GeV, probing gluons carrying a fraction x of nucleon momentum down to an unexplored regime of 6.5×10^{-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_{γN} 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.
2025
135
0
0
Chekhovsky, V.; Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Benato, L.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; D...espandi
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/1439463
Citazioni
  • ???jsp.display-item.citation.pmc??? 1
  • Scopus 3
  • ???jsp.display-item.citation.isi??? 2
social impact