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Inclusive e$^+$e$^-$ production has been studied with HADES in $\pi^-$ + p,$\pi^-$ + C and $\pi^- + \mathrm{CH}_2$ reactions, using the GSI pion beam at$\sqrt{s_{\pi p}}$ = 1.49 GeV. Invariant mass and transverse momentumdistributions have been measured and reveal contributions from Dalitz decays of$\pi^0$, $\eta$ mesons and baryon resonances. The transverse momentumdistributions are very sensitive to the underlying kinematics of the variousprocesses. The baryon contribution exhibits a deviation up to a factor sevenfrom the QED reference expected for the dielectron decay of a hypotheticalpoint-like baryon with the production cross section constrained from theinverse $\gamma$ n$\rightarrow \pi^-$ p reaction. The enhancement is attributedto a strong four-momentum squared dependence of the time-like electromagnetictransition form factors as suggested by Vector Meson Dominance (VMD). Twoversions of the VMD, that differ in the photon-baryon coupling, have beenapplied in simulations and compared to data. VMD1 (or two-component VMD)assumes a coupling via the $\rho$ meson and a direct coupling of the photon,while in VMD2 (or strict VMD) the coupling is only mediated via the $\rho$meson. The VMD2 model, frequently used in transport calculations for dileptondecays, is found to overestimate the measured dielectron yields, while a gooddescription of the data can be obtained with the VMD1 model assuming no phasedifference between the two amplitudes. Similar descriptions have also beenobtained using a time-like baryon transition form factor model where the pioncloud plays the major role.

Inclusive e$^+$e$^-$ production in collisions of pions with protons and nuclei in the second resonance region of baryons