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Compact Muon Solenoid
LHC, CERN

CMS-PAS-BPH-14-009
Dependence of the $\Upsilon$(nS) production ratios on charged particle multiplicity in pp collisions at $\sqrt{s}= $ 7 TeV
Abstract: The ratios of the cross section of the $\Upsilon$(nS) mesons with $|y|<1.2$ are studied as a function of the number of charged particles with $p_{\mathrm{T}}> $ 0.4 GeV and $|\eta|< $ 2.4 produced in pp collisions at $\sqrt{s}= $ 7 TeV. Evidence of a decrease of the ratios between the higher and the lower mass states is observed, that is more pronounced at lower $p_{\mathrm{T}}$. For $\Upsilon$(nS) mesons of transverse momentum greater than 7 GeV, this effect is studied as a function of the underlying event sphericity, and of the distribution of charged particles with respect to the $\Upsilon$(nS) direction.
CMS Publications
Compact Muon Solenoid
LHC, CERN