What information can we obtain from the yield ratio pi -/ pi + in heavy-ion collisions?

Abstract

Data on the {pi}{sup {minus}}/{pi}{sup +} ratio in heavy-ion collisions are analyzed by theoretical formula. It accounts for Coulomb interaction between central charged fragment consisting of stopped nucleons with effective charge {ital Z}{sub eff} and charged {pi}{close_quote}s. The Coulomb wave function method is used in order to account for the finite {pi} production range {beta}. For the Gaussian source function it results in a quasiscaling in {beta} and {ital Z}{sub eff}, which makes determination of {beta} and {ital Z}{sub eff} difficult. Only sufficiently accurate data taken in the extreme small {ital m}{sub {ital T}}{endash}{ital m}{sub {pi}} region, where this quasiscaling is broken, could be used for this purpose. {copyright} {ital 1996 The American Physical Society.}