Observation of the Charged-Particle Multiplicity Dependence of σ<sub>ψ(2<i>S</i>)</sub>/σ<sub><i>J</i>/ψ</sub> in <i>p</i>-Pb Collisions at 8.16 TeV
Creators
- 1. Yerevan Phys Inst, Yerevan, Armenia
- 2. Inst Hochenergiephys, Vienna, Austria
Description
Bound states of charm and anticharm quarks, known as charmonia, have a rich spectroscopic structure that can be used to probe the dynamics of hadron production in high-energy hadron collisions. Here, the cross section ratio of excited (psi(2S)) and ground state (J/psi) vector mesons is measured as a function of the charged-particle multiplicity in proton-lead (pPb) collisions at a center-of-mass (CM) energy per nucleon pair of 8.16 TeV. The data corresponding to an integrated luminosity of 175 nb(-1) were collected using the CMS detector. The ratio is measured separately for prompt and nonprompt charmonia in the transverse momentum range 6.5 < p(T) < 30 GeV and in four rapidity ranges spanning -2.865 < y(CM) < 1.935. For the first time, a statistically significant multiplicity dependence of the prompt cross section ratio is observed in proton-nucleus collisions. There is no clear rapidity dependence in the ratio. The prompt measurements are compared with a theoretical model which includes interactions with nearby particles during the evolution of the system. These results provide additional constraints on hadronization models of heavy quarks in nuclear collisions.
Files
bib-2a8cdac1-c2d0-4cb5-9632-c850d101cabd.txt
Files
(478 Bytes)
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