In-medium modification of π-mesons produced in heavy ion collisions

Abstract The mass shift Δ m ϱ and width broadening ΔΓ ϱ of ϱ mesons produced in heavy ion collisions is estimated using a general formula which relates the in-medium mass shift of a particle to the real part of the forward scattering amplitude Ref( E ) of this particle on constituents of the medium and ΔΓ to the corresponding cross section. It is found that in high energy ( E / A ⪸ 100 GeV) heavy ion collisions the ϱ width broadening is large and ϱ (or ω) peak could hardly be observed in + e − ( μ + μ − ) effective mass distributions. In low energy collisions ( E / A ∼ a few GeV) a broad (a few hundred MeV) enhancement is expected at the position of the ϱ peak.