Dilepton production at SIS energies
  In this short review the results of detailed studies for dilepton production from $p+A$ and $A+A$ reactions at SIS energies are presented. The calculations are based on a semi-classical BUU transport model that includes the off-shell propagation of vector mesons and evaluates the width of the vector mesons dynamically. Different scenarios of in-medium modifications of vector mesons, such as collisional broadening and dropping vector meson masses, are investigated and the possibilities for an experimental observation of in-medium effects in $p+A$ reactions at 1--4 GeV are discussed for a variety of nuclear targets. 
E.L. Bratkovskaya (Uni. Frankfurt)