We investigate the different contributions to the in-plane flow of K+ mesons
observed recently by the FOPI collaboration in the reaction Ni(1.93 AGeV)+Ni.
Due to the kinematics of the three body phase space decay the flow of kaons
produced in baryon-baryon interactions is smaller than that of the baryons in
the entrance channel. On the contrary, in pi N interactions the flow of the
sources and of the kaons are identical. Therefore the total kaon flow depends
on the relative number of Delta N -> K+ and pi N -> K+ reactions and hence on
the lifetime of the Delta, in addition to the already known dependence on the
potential interaction interaction of the kaons with the nuclear environment.Comment: 11 pages, 10 figures, submitted to NP
