Strangeness production in relativistic heavy-ion collisions

Kaon production in relativistic heavy-ion collisions is studied. Particular attention is paid to situations in which high densities are obtained, such as in the Brookhaven AGS experiments with 14.6 GeV/nucleon Si on Au. Because of the explicit chiral-symmetry breaking terms in chiral Langrangians, kaons acquire an effective mass mK* which goes to zero at the critical baryon density. Well before such densities, mK* is sufficiently reduced to greatly facilitate kaon production through processes like ππ→Kanti K. Previous expressions for the decreasing kaon mass were arrived at by linear chiral perturbation theory. Whereas we cannot systematically proceed to higher order, we use physical models to suggest how relevant quantities will behave in higher order. We present arguments that mK* effectively goes to zero in the present AGS experiments. (orig.)