Speaker
Description
The PHENIX collaboration has measured the ratio of the Psi(2s) to the
Psi(1s) cross section in p+p and p(3He)+A collisions at forward and
backward rapidity. We find that in p+p collisions, the data are
consistent with expectations from a modified color evaporation model
of quarkonia formation. In p(3He)+A collisions, in the p(3He)-going
direction, within uncertainties there is an equivalent nuclear
modification of both Psi states. However, in the A-going direction,
the nuclear modification factor of the weaker bound Psi(2s) is a
factor of 2 less than that of the Psi(1s). Since these states are not
fully formed until after they exit the nucleus, interactions between
the fully formed charmonia and co-moving hadrons may be responsible
for this effect, consistent with the higher particle density in the
A-going direction relative to the p(3He)-going direction. This
mechanism may compete with color screening in a deconfined plasma in
A+A collisions to produce sequential suppression of excited quarkonia
states.
Presentation type | Oral |
---|