WHAT INFORMATION CAN WE OBTAIN FROM THE YIELD RATIO PI(-) PI(+) IN HEAVY-ION COLLISIONS/

Data on the pi(-)/pi(+) ratio in heavy-ion collisions are analyzed by theoretical formula. It accounts for Coulomb interaction between centr al charged fragment consisting of stopped nucleons with effective char ge Z(eff) and charged pi's. The Coulomb wave function method is used i n order to account for the finite pi production range beta. For the Ga ussian source function it results in a quasiscaling in beta and Z(eff) , which makes determination of beta and Z(eff) difficult. Only suffici ently accurate data taken in the extreme small m(T)-m(pi) region, wher e this quasiscaling is broken, could be used for this purpose.