2020/07/31 by CMS Collaboration, A. M. Sirunyan, A. Tumasyan +98
Physics and Astronomy · #Astrophysics #Event (particle physics) #High-Energy Particle Collisions Research #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Production (economics) #Proton #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1007/jhep11(2020)001
published as JHEP 11 (2020) 001 · Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/BPH-14-009 (CMS Public Pages) [This release: include the author list.]
openalex created_date 2020/07/29 · openalex publication_date 2020/11/01 · arxiv created 2020/11/10 · arxiv updated 2020/11/11 · openalex updated_date 2026/08/05
A bstract The ratios of the production cross sections between the excited ϒ(2S) and ϒ(3S) mesons and the ϒ(1S) ground state, detected via their decay into two muons, are studied as a function of the number of charged particles in the event. The data are from proton-proton collisions at √(s) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt></mml:math> = 7 TeV, corresponding to an integrated luminosity of 4.8 fb − 1 , collected with the CMS detector at the LHC. Evidence of a decrease in these ratios as a function of the particle multiplicity is observed, more pronounced at low transverse momentum pT\upmu \upmu <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi>p</mml:mi><mml:mi>T</mml:mi><mml:mi>μμ</mml:mi></mml:msubsup></mml:math> . For ϒ(nS) mesons with pT\upmu \upmu <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi>p</mml:mi><mml:mi>T</mml:mi><mml:mi>μμ</mml:mi></mml:msubsup></mml:math> > 7 GeV, where most of the data were collected, the correlation with multiplicity is studied as a function of the underlying event transverse sphericity and the number of particles in a cone around the ϒ(nS) direction. The ratios are found to be multiplicity independent for jet-like events. The mean pT\upmu \upmu <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi>p</mml:mi><mml:mi>T</mml:mi><mml:mi>μμ</mml:mi></mml:msubsup></mml:math> values for the ϒ(nS) states as a function of particle multiplicity are also measured and found to grow more steeply as their mass increases.