Centrality Scaling of the $p_T$ Distribution of Pions

Abstract

From the preliminary data of PHENIX on the centrality dependence of the ${\pi }^0$ spectrum in $p_T$ at midrapidity in heavy-ion collisions, we show that a scaling behavior exists that is independent of the centrality. It is then shown that $<p_T>$ degrades with increasing $N_{\mathrm{part}}$ exponentially with a decay constant that can be quantified. A scaling distribution in terms of an intuitive scaling variable is derived that is analogous to the KNO scaling. No theoretical models are used in any part of this phenomenological analysis.

Comments: 4 pages RevTex, 5 figures included