First measurement of the strange particles Rcp nuclear modification factors in heavy-ion collisions at the SPS

The NA57 experiment has measured the pt distributions of K0s, Lambda, and antiLambda particles in fixed-target Pb-Pb interactions at sqrt(s_{NN})=17.3 GeV as a function of the collision centrality. In this paper we study the central-to-peripheral nuclear modification factors and compare them to other measurements and to theoretical predictions.