Kaon Modification in Pion Medium

Abstract Kaon properties in thermal pion-nucleon medium are studied. The dense pion-nucleon medium is produced in high-energy heavy-ion collisions. The consideration is based on the chiral nucleon-kaon-pion Lagrangian. It is found that the pion medium does not produce a substantive contribution but enhances the effect of the baryon matter. Numerical estimate shows that this enhancement factor induced by the pion medium does not exceed 5% at the freeze-out stage of heavy-ion collisions, i.e., it is small. However, the impact of this enhancement can be higher in actual nuclear collisions because the effect of the in-medium (anti)kaon modification is accumulated during the (anti)kaon evolution before the freeze-out when the pion density is higher.