Suppression of high-p_T neutral pion production in Central Pb+Pb collisions at √s_NN=17.3 GeV relative to p+C and p+Pb collisions

Abstract

Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at √s_NN=17.4 GeV at midrapidity (2.3≲η_lab≲3.0) over the range 0.7≲p_T≲3.5 GeV/c. The spectra are compared to π⁰ spectra measured in Pb+Pb collisions at √s_NN=17.3 GeV in the same experiment. For a wide range of Pb+Pb centralities (N_part≲300), the yield of π⁰'s with p_T≳2 GeV/c is larger than or consistent with the p+C or p+Pb yields scaled with the number of nucleon-nucleon collisions (N_coll), while for central Pb+Pb collisions with N_part≳350, the π⁰ yield is suppressed.