Compact Muon Solenoid
LHC, CERN
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| CMS-PAS-HIN-15-001 | ||
| Nuclear modification of $\Upsilon$ states in PbPb | ||
| CMS Collaboration | ||
| June 2015 | ||
| Abstract: Yields of $\Upsilon$(1S), $\Upsilon$(2S) and $\Upsilon$(3S) mesons are measured in the CMS experiment via their $\mu^+ \mu^-$ decays, for bottomonium rapidity $|y|<$ 2.4, in PbPb and pp collisions at the same energy, $\sqrt{s_{\mathrm{ NN}}} =$ 2.76 TeV. The CMS detector was used to collect integrated luminosity of 166 $\mu$b$^{-1}$ for PbPb and 5.4 pb$^{-1}$ for pp, corresponding to a similar total number of nucleon-nucleon collisions. Differential cross sections and nuclear modification factors are reported as functions of rapidity and transverse momentum, as well as collision centrality, for the $\Upsilon$(1S) and the $\Upsilon$(2S). By comparing to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions, a strong, centrality-dependent suppression is observed in PbPb collisions, by up to a factor of 2 and 10, for the $\Upsilon$(1S) and the $\Upsilon$(2S), respectively. No significant dependences are observed as functions of rapidity or transverse momentum. The $\Upsilon$(3S) was not observed in PbPb collisions, being suppressed by more than 7 at the 95% confidence level. | ||
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Links:
CDS record (PDF) ;
inSPIRE record ;
Public twiki page ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, PLB 770 (2017) 357. The superseded preliminary plots can be found here. |
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Compact Muon Solenoid LHC, CERN |
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