Sprecher
Beschreibung
Measurements of bottomonium states in heavy-ion collisions provide a powerful tool to study both initial-state effects on heavy-quark production and final-state interactions between heavy quarks and the quark-gluon plasma (QGP). The ATLAS experiment at LHC has measured the production of bottomonium states $\Upsilon$(1S), $\Upsilon$(2S), and $\Upsilon$(3S), in Pb+Pb and $pp$ collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data correspond to integrated luminosities of 1.38 nb$^{-1}$ of Pb+Pb data collected in 2018, 0.44 nb$^{-1}$ of Pb+Pb data collected in 2015, and 0.26 fb$^{-1}$ of pp data collected in 2017. The final ATLAS result on the production of three bottomonium states will be reported. The measurement in Pb+Pb collisions is compared to that in $pp$ collisions to extract the nuclear modification factor, $R_{\mathrm{AA}}$, as a function of event centrality, $p_{\mathrm{T}}$ and rapidity, and compared to several theoretical models. We will also present a new measurement studying the relationship between the production of hard and soft particles through the correlation of Upsilon meson states with the inclusive-charged particle yields. The analysis is performed using the full-luminosity ATLAS Run-2 13 TeV $pp$ data. A description of the technical challenges associated with a heavy-ion style analysis in high-pileup $pp$ data will be shown, as well as the results and their physics implications.
Affiliation
ATLAS Collaboration
| Experiment/Theory | ATLAS |
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