UC San Diego

The nuclear modification factors of J/ψ$${\mathrm {J}/\psi }$$ and ψ(2S)$$\psi \text {(2S)}$$ mesons are measured in PbPb$$\text {PbPb}$$ collisions at a centre-of-mass energy per nucleon pair of sNN=5.02TeV$$\sqrt{\smash [b]{s_{_{\text {NN}}}}} = 5.02\,\text {Te}\text {V} $$. The analysis is based on PbPb$$\text {PbPb}$$ and pp$$\mathrm {p}\mathrm {p}$$ data samples collected by CMS at the LHC in 2015, corresponding to integrated luminosities of 464μb-1$$\,\mu \mathrm {b}^{-1}$$ and 28pb-1$$\,\text {pb}^\text {-1}$$, respectively. The measurements are performed in the dimuon rapidity range of |y|<2.4$$|y | < 2.4$$ as a function of centrality, rapidity, and transverse momentum (pT$$p_{\mathrm {T}}$$ ) from pT=3$$p_{\mathrm {T}} =3$$GeV/c$${\,\text {Ge}\text {V}/}\text {c}$$ in the most forward region and up to 50GeV/c$${\,\text {Ge}\text {V}/}\text {c}$$. Both prompt and nonprompt (coming from b hadron decays) J/ψ$${\mathrm {J}/\psi }$$ mesons are observed to be increasingly suppressed with centrality, with a magnitude similar to the one observed at sNN=2.76TeV$$\sqrt{\smash [b]{s_{_{\text {NN}}}}} = 2.76\,\text {Te}\text {V} $$ for the two J/ψ$${\mathrm {J}/\psi }$$ meson components. No dependence on rapidity is observed for either prompt or nonprompt J/ψ$${\mathrm {J}/\psi }$$ mesons. An indication of a lower prompt J/ψ$${\mathrm {J}/\psi }$$ meson suppression at pT>25$$p_{\mathrm {T}} > 25$$GeV/c$${\,\text {Ge}\text {V}/}\text {c}$$ is seen with respect to that observed at intermediate pT$$p_{\mathrm {T}}$$. The prompt ψ(2S)$$\psi \text {(2S)}$$ meson yield is found to be more suppressed than that of the prompt J/ψ$${\mathrm {J}/\psi }$$ mesons in the entire pT$$p_{\mathrm {T}}$$ range.