Relatore
Descrizione
A very important contribution of dilepton production in pion-nucleon collisions comes from the Dalitz decay of s-channel baryon resonances, R->Ne+e-. These dileptons originate from a virtual photon with small timelike squared four-momentum q^2, therefore the study of this reaction gives access to the electromagnetic interaction of baryon resonances in a kinematical domain inaccessible elsewhere. In this contribution we discuss what space-time symmetries teach us about the anisotropy of dileptons in pi+N -> Ne+e-. Then we present an effective Lagrangian model and its predictions for the cross section of the reaction. This work is motivated by recent pion-beam experiments of the HADES collaboration at the CM energy of 1.49 GeV where baryons of the second resonant region are expected to give important contributions.
