Transverse momentum distributions of neutral pions from nuclear collisions at 200 AGeV

New results on transverse mass spectra of neutral pions measured at central rapidity are presented for impact parameter selected 200 A.GeV S + S and S + Au collisions. The distributions cover more than 8 orders of magnitude in cross section over the range 0.3 GeV/c less than or equal to p(T) less than or equal to 4.0 GeV/c. Detailed comparisons to results from pp collisions are made. The spectra from all systems show a clear power-law like shape with similar curvature. Collisions of S + Au exhibit a larger mean transverse momentum than pp increasing with centrality. Predictions of string models and by hydrodynamic approaches including collective expansion and decays of short lived resonances are compared to the data and the implications are discussed.