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The results of midrapidity (0 < y < 0.8) neutral pion spectra over an extended transverse momentum range (1 < p T < 12 GeV/c) in √ s NN = 200 GeV Au + Au collisions, measured by the STAR experiment, are presented. The neutral pions are reconstructed from photons measured either by the STAR Barrel Electro-Magnetic Calorimeter or by the Time Projection Chamber via tracking of conversion electron-positron pairs. Our measurements are compared to previously published π ± and π 0 results. The nuclear modification factors R CP and R AA of π 0 are also presented as a function of p T . In the most central Au + Au collisions, the binary collision scaled π 0 yield at high p T is suppressed by a factor of about 5 compared to the expectation from the yield of p + p collisions. Such a large suppression is in agreement with previous observations for light quark mesons and is consistent with the scenario that partons suffer considerable energy loss in the dense medium formed in central nucleus-nucleus collisions at the Relativistic Heavy Ion Collider.

Rapidity-odd directed flow (v1) measurements for charged pions, protons and antiprotons near mid-rapidity (y = 0) are reported in

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We report precision measurements of the Feynman x (xF) dependence, and first measurements of the transverse momentum (pT) dependence, of transverse single-spin asymmetries for the production of pi0 mesons from polarized proton collisions at sqrt[s] = 200 GeV. The xF dependence of the results is in fair agreement with perturbative QCD model calculations that identify orbital motion of quarks and gluons within the proton as the origin of the spin effects. Results for the pT dependence at fixed xF are not consistent with these same perturbative QCD-based calculations.