Centrality, rapidity and transverse momentum dependence of $J/ψ$ suppression in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$=2.76 TeV

ALICE Collaboration

The inclusive $J/\psi$ nuclear modification factor $R_{\rm AA}$ in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$=2.76 TeV has been measured by ALICE as a function of centrality in the e$^+$e$^-$ decay channel at mid-rapidity $|y|<0.8$ and as a function of centrality, transverse momentum and rapidity in the $\mu^{+}\mu^{-}$ decay channel at forward-rapidity $2.5


Figure 1

Top panels: invariant mass distributions for opposite-sign (OS) and mixed-events (ME) electron pairs. Bottom panels: OS invariant mass spectra, after the subtraction of the ME distributions, with a comparison to the Monte Carlo signal (solid lines) superimposed. The MC signal is scaled to match the integral of the OS distribution within the mass counting window. From left to right, distributions correspond to the centrality ranges 0-10%,10-40% and 40-90%, respectively. The panels for the 0-10% and 10-40% centrality ranges are obtained from the 2011 data, while the ones for the 40-90% centrality range are obtained from the 2010 data. The two vertical dashed lines shown in each panel indicate the mass interval used for signal counting.
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Figure 2

Top panels: fits of the dimuon invariant mass spectra in selected $\pt$ intervals. Bottom panels: idem after subtraction of the combinatorial background with the event mixing technique. Distributions correspond to the centrality class 0-90\% and $2.5< y< 4$.
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Figure 3

Centrality dependence of the nuclear modification factor, $\Raa$ of inclusive $\jpsi$ production in Pb-Pb collisions at $\snn=2.76$ GeV, measured at mid-rapidity and at forward-rapidity. The point to point uncorrelated systematic uncertainties (type II) are represented as boxes around the data points, while the statistical ones are shown as vertical bars. Global correlated systematic uncertainties (type I) are quoted directly in the legend.
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Figure 4

Top panel: transverse momentum dependence of the centrality integrated $\jpsi$ $\Raa$ measured by ALICE in Pb-Pb collisions at $\snn=2.76$ GeV compared to CMS results at the same $\snn$. Bottom panel: transverse momentum dependence of the $\jpsi$ $\Raa$ measured by ALICE in the $0-20%$ most central Pb-Pb collisions at $\snn=2.76$ compared to PHENIX results in the 0-20% most central Au-Au collisions at $\snn=0.2$ TeV.
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Figure 5

The rapidity dependence of the $\jpsi$ $\Raa$ measured in Pb-Pb collisions at $\snn=2.76$. Both mid- and forward-rapidity measurements include a common correlated systematic uncertainty of 3.4% due to $T_{AA}$. The mid-rapidity measurement covers the rapidity range $|y|< 0.8$ and the forward-rapidity one is given in intervals of 0.25 unit of rapidity from $y=2.5$ to $y=4$.
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