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Excited charmonium suppression in proton-nucleus collisions as a consequence of comovers

E. G. Ferreiro

Abstract

Recent results from proton(deuteron)-nucleus collisions at RHIC and LHC energies have shown an unexpected suppression of excited quarkonium states as compared to their ground states. In particular, stronger suppression of the $ψ(2S)$ relative to the $J/ψ$ has been detected. Similar observations were made at lower energies and were easily explained by nuclear absorption. At higher energies, a similar explanation would violate the Heisenberg principle, since the calculations based on the uncertainty principle lead to a charmonium formation time expected to be larger than the nuclear radius, which results in identical nuclear break-up probability for the $ψ(2S)$ and $J/ψ$. On the contrary, this behavior is naturally explained by the interactions of the quarkonium states with a comoving medium. We present our results on $J/ψ$ and $ψ(2S)$ production for d+Au collisions at $\sqrt{s}=200$ GeV and for p+Pb collisions at $\sqrt{s}=5.02$ TeV.

Excited charmonium suppression in proton-nucleus collisions as a consequence of comovers

Abstract

Recent results from proton(deuteron)-nucleus collisions at RHIC and LHC energies have shown an unexpected suppression of excited quarkonium states as compared to their ground states. In particular, stronger suppression of the relative to the has been detected. Similar observations were made at lower energies and were easily explained by nuclear absorption. At higher energies, a similar explanation would violate the Heisenberg principle, since the calculations based on the uncertainty principle lead to a charmonium formation time expected to be larger than the nuclear radius, which results in identical nuclear break-up probability for the and . On the contrary, this behavior is naturally explained by the interactions of the quarkonium states with a comoving medium. We present our results on and production for d+Au collisions at GeV and for p+Pb collisions at TeV.

Paper Structure

This paper contains 5 equations, 4 figures.

Figures (4)

  • Figure 1: (Color online) The $J/\psi$ (blue continuous line) and $\psi(2S)$ (red continuous line) nuclear modification factor $R_{dAu}$ as a function of the number of collisions $N_{coll}$ compared to the PHENIX data Adare:2013ezl. The suppression due to the shadowing corrections (discontinuous line) is also shown.
  • Figure 2: (Color online) The $J/\psi$ (blue line) and $\psi(2S)$ (red line) nuclear modification factor $R_{pPb}$ as a function of rapidity compared to the ALICE data Abelev:2014zpa. The suppression due to the shadowing corrections (discontinuous line) is also shown.
  • Figure 3: (Color online) The $J/\psi$ (upper figure) and $\psi(2S)$ (lower figure) nuclear modification factor $R_{pPb}$ as a function of the number of collisions in the backward $-4.46<y<-2.96$ (blue continuous line) and forward $2.03<y<3.53$ (red continuous line) rapidity intervals. The modification due to the antishadowing corrections in the backward region (blue discontinuous line) and to the shadowing corrections in the forward region (red discontinuous line) is also shown.
  • Figure 4: (Color online) The ratio of the $\psi(2S)$ over $J/\psi$ nuclear modification factors $R_{pPb}^{\psi(2S)}/R_{pPb}^{J/\psi}$ as a function of the number of collisions in the backward $-4.46<y<-2.96$ (blue continuous line) and forward $2.03<y<3.53$ (red continuous line) rapidity intervals. .