CMS Collaboration2015-04-212015-04-212014CMS Collaboration. "Measurement of Prompt ψ(2S) to J/ψ Yield Ratios in Pb-Pb and p-p Collisions at √sNN=2.76  TeV." <i>Physical Review Letters,</i> 113, (2014) American Physical Society: 262301. http://dx.doi.org/10.1103/PhysRevLett.113.262301.https://hdl.handle.net/1911/79635The ratio between the prompt ψ(2S) and J/ψ yields, reconstructed via their decays into μ+μ−, is measured in Pb-Pb and p-p collisions at √sNN=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−1 and 5.4  pb−1, respectively. The double ratio of measured yields (Nψ(2S)/NJ/ψ)Pb−Pb/(Nψ(2S)/NJ/ψ)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<pT<30  GeV/c, and the other at forward rapidity, 1.6<|y|<2.4, extending to lower pT values, 3<pT<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.engThis article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Journal articlehttp://dx.doi.org/10.1103/PhysRevLett.113.262301