Physical Review Letters
For Au þ Au collisions at 200 GeV, we measure neutral pion production with good statistics for transverse momentum, pT, up to 20 GeV=c. A fivefold suppression is found, which is essentially constant for 5 < pT < 20 GeV=c. Experimental uncertainties are small enough to constrain any model-dependent parametrization for the transport coefficient of the medium, e.g., hq^i in the parton quenching model. The spectral shape is similar for all collision classes, and the suppression does not saturate in Au þ Au collisions.
Adare, A., Afanasiev, S., Aidala, C., Ajitanand, N. N., Akiba, Y., Al-Bataineh, H., . . . Zolin, L. (2008). Suppression pattern of neutral pions at high transverse momentum in Au+Au collisions at sNN=200GeV and constraints on medium transport coefficients. Physical Review Letters, 101(23)