Measuring the Upsilon Nuclear Modification Factor at STAR

Understand

Suppression of quarkonia in heavy ion collisions with respect to proton-proton collisions due to the Debye screening of the potential between the heavy quarks was hypothesized to be a signature of the Quark Gluon Plasma (QGP).

• However, other effects besides Debye screening, such as the statistical recombination of quark anti-quark heavy flavor pairs, or co-mover absorption can also affect quarkonia production in heavy ion collisions.
• Quantifying the suppression of an entire family of quarkonium mesons can give us a model dependent constraint on the temperature.
• The suppression of Upsilon can be quantified by calculating the Nuclear Modification factor, RAA, which is the ratio of the production in Au+Au collisions to the production in p+p scaled by the number of binary collisions.