CMS-HIN-12-007

CMS-HIN-12-007 ; CERN-PH-EP-2014-240
Measurement of prompt $\psi(2\mathrm{S})$ to $\mathrm{J}/\psi$ yield ratios in PbPb and pp collisions at $\sqrt{s_\mathrm{NN}}$ = 2.76 TeV
CMS Collaboration
8 October 2014
Phys. Rev. Lett. 113 (2014) 262301
Abstract: The ratio between the prompt $\psi(2\mathrm{S})$ and $\mathrm{J}/\psi$ yields, reconstructed via their decays into $\mu^+\mu^-$ , is measured in PbPb and pp collisions at $\sqrt{s_\mathrm{NN}}$ = 2.76 TeV. The analysis is based on PbPb and pp data samples collected by CMS at the LHC, corresponding to integrated luminosities of 150 $\mu \mathrm{b}^{-1}$ and 5.4 $\mathrm{pb}^{-1}$ , respectively. The double ratio of measured yields, $( N_{\psi(2\mathrm{S})} / N_{ \mathrm{J} / \psi} )_{ \mathrm{Pb} \mathrm{Pb} } / ( N_{ \psi( 2 \mathrm{S} ) } / N_{ \mathrm{J} / \psi} )_{ \mathrm{p} \mathrm{p} }$ , is computed in three PbPb collision centrality bins and two kinematic ranges: one at midrapidity, $\| y \| <$ 1.6, covering the transverse momentum range 6.5 $< p_{\mathrm{T}} <$ 30 GeV/ $c$ , and the other at forward rapidity, 1.6 $< \| y \| <$ 2.4, extending to lower $p_{\mathrm{T}}$ values, 3 $< p_{\mathrm{T}} <$ 30 GeV/ $c$ . The centrality-integrated double ratio changes from 0.45 $\pm$ 0.13 (stat) $\pm$ 0.07 (syst) in the first range to 1.67 $\pm$ 0.34 (stat) $\pm$ 0.27 (syst) in the second. This difference is most pronounced in the most central collisions.
Links: e-print arXiv:1410.1804 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; Public twiki page ; HepData record ; CADI line (restricted) ;

Figures	CMS Publications

Figures
png pdf	Figure 1-a:
png pdf	Figure 1-b:
png pdf	Figure 1-c:
png pdf	Figure 1-d:
png pdf	Figure 2: