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 s=200 GeV and for
p+Pb collisions at s=5.02 TeV.Comment: 7 pages, 5 figures. Extended version, figures unchanged. Accepted for
publication in Physics Letters