Radial flow of kaon mesons in heavy ion reactions

Abstract

This work investigates the collective motion of kaons in heavy ion reactions at SIS energies (about 1-2 GeV/nucleon). A radial collective flow of $K^{+}$ mesons is predicted to exist in central Au + Au collisions, which manifests in a characteristic "shoulder-arm" shape of the transverse mass spectrum of the midrapidity $K^{+}$ mesons. The $K^{+}$ radial flow arises from the repulsive $K^{+}$ mean field in nuclear matter. In spite of a strong reabsorption and rescattering the attractive $K^{-}$ mean field leads as well to a collective radial flow of $K^{-}$ mesons. The $K^{-}$ radial flow, however, is different from that of $K^{+}$ mesons and can be observed by a characteristic "concave" structure of the transverse mass spectrum of the $K^{-}$ mesons emitted at midrapidity. The kaon radial flows can therefore serve as a novel tool for the investigation of kaon properties in dense nuclear matter.

Comments: 30 pages RevTex, 5 PS figures, accepted for publication in Phys. Rev. C