From production to suppression, a critical review of charmonium measurements at RHIC

Understand

Charmonium suppression in hot and dense nuclear matter has been argued to be a signature for the production of the quark gluon plasma (QGP).

• In order to search for this effect in heavy ion collisions one must have a clear understanding of all the factors that can contribute to such a suppression.
• These may include shadowing of the partons in a nuclear environment, breakup of a correlated $c-\bar{c}$ pair as it traverses the nuclear fragment, suppression of feed-down from higher mass states as well as other initial state interactions.
• In order to disentangle these effects one must measure charmonium production rates in both proton+proton (p+p) and proton+nucleus (p+A) collisions.