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| CMS-PAS-HIN-24-021 | ||
| Measurement of the top quark pair production cross section in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.36 TeV | ||
| CMS Collaboration | ||
| 2025-09-09 | ||
| Abstract: The first measurement of the production cross section of top quark pairs ($ {\rm t\bar{t}} $) in lead-lead collisions at $ \sqrt{s_{\rm NN}}= $ 5.36 TeV is presented. The data were collected by the CMS experiment in 2023, corresponding to an integrated luminosity of 1.58 nb$ ^{-1} $. A cross section of $ \sigma_{\rm t\bar{t}} = 3.42 ^{+0.54}_{-0.50} {\rm (stat)} ^{+0.50}_{-0.43} {\rm (syst)} \mu{\rm b} $ is measured from a fit to a multivariate discriminator based on the lepton kinematic distributions and the number of jets associated with bottom quarks, and found to be in agreement with predictions using state-of-the-art nuclear parton distribution functions. In addition, the ratio of the $ {\rm t\bar{t}} $ to Drell-Yan (DY) cross sections is determined to be $ R_{\rm t\bar{t}/Z} = 0.0086 ^{+0.0014}_{-0.0013} {\rm (stat)} ^{+0.0011}_{-0.0010} {\rm (syst)} $, with improved precision relative to the $ \sigma_{\rm t\bar{t}} $ extraction and in agreement with predictions. Both $ \sigma_{\rm t\bar{t}} $ and $ R_{\rm t\bar{t}/Z} $ are measured as function of the centrality, a quantity which quantify the degree of overlap between the colliding nuclei. | ||
| Links: CDS record (PDF) ; CADI line (restricted) ; | ||
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Compact Muon Solenoid LHC, CERN |
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