Measurement of Prompt ψ(2S) to J/ψ Yield Ratios in Pb-Pb and p-p Collisions at √s[subscript NN] = 2.76 TeV
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PhysRevLett.113.262301.pdf
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Author(s)
Khachatryan, V.
Sirunyan, A. M.
Tumasyan, A.
Adam, W.
Bergauer, T.
Dragicevic, M.
Erö, J.
Fabjan, C.
Friedl, M.
Frühwirth, R.
Date Issued
December 2014
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Khachatryan, V., et al. "Measurement of Prompt ψ(2S) to J/ψ Yield Ratios in Pb-Pb and p-p Collisions at √s[subscript NN] = 2.76 TeV." Phys. Rev. Lett. 113, 262301 (December 2014). © 2014 CERN, for the The CMS Collaboration
Version
Final published version
Abstract
The ratio between the prompt ψ(2S) and J/ψ yields, reconstructed via their decays into μ[superscript +]μ[superscript -], is measured in Pb-Pb and p-p collisions at √s[subscript NN] = 2.76 TeV. The analysis is based on Pb-Pb and p-p data samples collected by CMS at the Large Hadron Collider, corresponding to integrated luminosities of 150 μb[superscript -1] and 5.4 pb[superscript -1], respectively. The double ratio of measured yields (N[subscript ψ(2S)]/N[subscript J/ψ])[subscript Pb-Pb]/(N[subscript ψ(2S)]/N[subscript J/ψ])[subscript P-P] is computed in three Pb-Pb collision centrality bins and two kinematic ranges: one at midrapidity, |y| < 1.6, covering the transverse momentum range 6.5 < p[subscript T] < 30 GeV/c, and the other at forward rapidity, 1.6 < |y| < 2.4, extending to lower p[subscript T] values, 3 < p[subscript T] < 30 GeV/c. The centrality-integrated double ratio changes from 0.45 ± 0.13(stat) ± 0.07(syst) in the first range to 1.67 ± 0.34(stat) ± 0.27(syst) in the second. This difference is most pronounced in the most central collisions.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
Massachusetts Institute of Technology. School of Science
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DOI of Published Version
http://dx.doi.org/10.1103/PhysRevLett.113.262301
