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 = 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)μμ. For ϒ(nS) mesons with (pT)μμ> 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)μμ 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.

Investigation into the event-activity dependence of ϒ(nS) relative production in proton-proton collisions at √s = 7 TeV

Vagnerini A.;Meridiani P.;Amapane N.;Argiro S.;Bellan R.;Bellora A.;Cappati A.;Costa M.;Covarelli R.;Kiani B.;Migliore E.;Monaco V.;Monteil E.;Obertino M. M.;Pacher L.;Pinna Angioni G. L.;Romero A.;Salvatico R.;Sola V.;Solano A.;Soldi D.;Shchelina K.;Rumerio P.;Ravera F.;
2020-01-01

Abstract

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 = 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)μμ. For ϒ(nS) mesons with (pT)μμ> 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)μμ 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.
2020
2020
11
1
39
B physics; Hadron-Hadron scattering (experiments); Particle correlations and fluctuations; Quarkonium
Sirunyan A.M.; Tumasyan A.; Adam W.; Ambrogi F.; Bergauer T.; Dragicevic M.; Ero J.; Escalante Del Valle A.; Flechl M.; Fruhwirth R.; Jeitler M.; Kram...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1846197
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