e+e- pairs from π-A reactions

الأصل · EN

We present a dynamical study of e+e- production in π-A reactions at 1.3 and 1.7 GeV on the basis of the Coupled-Channel-BUU approach. The contributions from vector mesons (ρ,ω) are calculated taking into account the collisional broadening effect and are compared to background sources in the dilepton spectrum from the Dalitz decays of ω and η mesons produced in the reaction. Two possible scenarios for the medium modifications of the vector mesons are investigated, i.e. the 'dropping mass' scheme for the ρ and ω and a momentum dependent ρ-meson spectral function that includes the polarization of the ρ-meson due to resonant ρ-N scattering.