Investigation into the event-activity dependence of ϒ(nS) relative production in proton-proton collisions at $$ \sqrt{s} $$ = 7 TeV

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 $$ \sqrt{s} $$ 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 $$ {p}_{\mathrm{T}}^{\upmu \upmu} $$ p T μμ . For ϒ(nS) mesons with $$ {p}_{\mathrm{T}}^{\upmu \upmu} $$ p T 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 $$ {p}_{\mathrm{T}}^{\upmu \upmu} $$ p T 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.

Can Transverse Mass Scaling Shed Light on the Event-Activity Dependence of $Υ$ Mesons Production at LHC?

“…The observations reported here may share a common origin with the results reported in [10]. The CMS collaboration measured the production of Υ (nS) mesons at √ s = 7 GeV as a function of the charged particle multiplicity in the underlying event.…”

“…Various extensions of the transverse-mass scaling incorporate different assumptions and are capable of describing a broad variety of experimental data with impressive precision [8]. In this letter, a more qualitative approach is presented providing a plausible corollary to measurements of Υ mesons made by the CMS experiment in pp collisions [9,10]. CMS observed an intriguing correlation between the order of the Υ (nS)-meson state and the multiplicity of charged hadrons measured in the collision, and suggested that this may correspond to a suppression of the excited Υ (nS) states in pp collisions.…”

Heavy quarks and jets as probes of the QGP

“…The most discussed explanations for the excited state quarkonium production modification with respect to the ground states are rescattering phenomena, either of partonic or hadronic nature [290,369,[520][521][522], as well as applying transport equation approaches [523,524] as employed in nucleus-nucleus collisions. In order to investigate these phenomena, ratios or self-normalized double ratios of different states have been measured in pp collisions as a function of a number of charged tracks in the event or forward energy deposition [525,526].…”

A technique to study the elastic and inelastic interaction of quarkonium with hadrons using femtoscopic correlations

“…Therefore, ϒhadron correlation studies will be feasible within the LHCb experiment. Moreover, the CMS experiment is expected to register around 1.7 million of ϒ in the LHC Run 3 [59], providing another opportunity for ϒ-hadron femtoscopy.…”