Central-to-peripheral nuclear modification factors in Pb-Pb collisions at ?(S_NN )=17.3 GeV

We present central-to-peripheral nuclear modification factors, R-CP, for the (PT) distributions of K-S(0), Lambda, Lambda, 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 K-S(0) and Lambda R-CP((PT)) are similar in shape to those measured at root sNN = 200 GeV at RHIC, though they are larger in absolute value. We have compared our K-S(0) R-CP data to a theoretical calculation. The prediction overestimates the data at (PT) approximate to 3-4 GeV/c, unless sizeable parton energy loss is included in the calculation. (c) 2005 Elsevier B.V. All rights reserved.