Elliptic emission of K+ in 158A GeV Pb+Pb collisions

Abstract We have studied the azimuthal angle distributions of identified charged particles near mid-rapidity region in semi-central Pb+Pb collisions at SPS energies. Our preliminary results show that π + mesons and protons seem to be emitted in the reaction plane, while out-of-plane for K + mesons. This phenomenon might be explained by the existence of another possible effect such as in-medium potential as well as the collective motion.