Central-to-peripheral nuclear modification factors in Pb-Pb collisions at sNN=17.3GeV

We present central-to-peripheral nuclear modification factors, RCP, for the pT distributions of KS0, Λ, Λ¯, and negatively charged particles, measured at central rapidity in Pb-Pb collisions at top SPS energy. The data cover the 55% most central fraction of the inelastic cross section. The KS0 and Λ RCP(pT) are similar in shape to those measured at sNN=200GeV at RHIC, though they are larger in absolute value. We have compared our KS0RCP data to a theoretical calculation. The prediction overestimates the data at pT≈3-4GeV/c, unless sizeable parton energy loss is included in the calculation.