Event activity dependence of relative Y(nS) production in pPb collisions at 8.16 TeV

CMS Physics Analysis Summaries
Report number	CMS-PAS-HIN-25-005
Title	Event activity dependence of relative Y(nS) production in pPb collisions at 8.16 TeV
Corporate author(s)	CMS Collaboration
Collaboration	CMS Collaboration
Subject category	Nuclear Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; CMS
Abstract	The relative production of the excited bottomonium states, $\Upsilon$(2S) and $\Upsilon$(3S), with respect to the ground state $\Upsilon$(1S) is measured via the dimuon decay channel in proton-lead collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_\mathrm{NN}} =$ 8.16 TeV. The analysis is based on data collected in 2016 with the CMS detector at the LHC, corresponding to an integrated luminosity of $175\,\text{nb}^{-1}$. The measurements are performed as functions of event activity, characterized by the charged-particle multiplicity measured within the pseudorapidity range $\|\eta\| < 2.4$, as well as the total transverse energy deposited in the forward region $4.0 < \|\eta\| < 5.2$. A decreasing behavior of the excited-state to ground-state yield ratios is observed with increasing charged-particle multiplicity and forward transverse energy. The measurements are compared with theoretical predictions that consider interactions of bottomonium states either with nearby particles produced in the same collision or with a hot medium that may form during the system evolution. The results provide new constraints on models describing the hadronization and modification of heavy quarks in nuclear collisions.
Email contact: cms-pag-conveners-heavyions@cern.ch Fulltext in PDF Figure_009-b Figure_009-a Figure_007-a Figure_008 Figure_001-b Figure_006-a Figure_006-b Figure_004-b Figure_010-a Figure_004-a Figure_011 Figure_005 Figure_010-b Figure_003 Figure_002 Figure_001-a Figure_007-b Additional information for the analysis (restricted access)