Compact Muon Solenoid
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| CMS-PAS-HIN-24-013 | ||
| First measurement of coherent photoproduction of $ \Upsilon(\mathrm{1S}) $ mesons in lead-lead ultraperipheral collisions at $ \sqrt{s_{\mathrm{NN}}} = $ 5.02 TeV | ||
| CMS Collaboration | ||
| 6 May 2025 | ||
| Abstract: Coherent photoproduction of heavy-flavor vector mesons in ultrarelativistic heavy ion collisions (UPCs) provides a direct probe of the gluonic structure of nuclei. This note presents the first measurement of coherent photoproduction of $ \Upsilon(1S) $ off heavy nuclei. The analysis uses 1.66 nb$^{-1}$ of data collected by the CMS experiment in 2018 at the CERN LHC in lead-lead collisions at a center-of-mass energy per nucleon-nucleon pair of 5.02 TeV. The differential cross section for coherent $ \Upsilon(1S) $ is presented as a function of rapidity ($ |y| $) up to $ |y| < $ 2.4. At photon-nucleus center-of-mass energies per nucleon $ W_{\gamma \mathrm{N}}^{\mathrm{Pb}} \approx $ 200 GeV, the coherent $ \Upsilon(1S) $ photoproduction cross section is found to be significantly suppressed compared to the expected results from $ \gamma $-proton interactions. Results of this study are compared to theoretical calculations based on quantum chromodynamics. | ||
| Links: CDS record (PDF) ; CADI line (restricted) ; | ||
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Compact Muon Solenoid LHC, CERN |
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