$e^+e^-$ production in $p A$ reactions at SIS energies

Abstract

Detailed predictions for dilepton production from $p A$ reactions at SIS energies are presented within a semi-classical BUU transport model that includes the off-shell propagation of vector mesons nonperturbatively and calculates 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.

38 pages, LaTeX, including 20 postscript figures, to be published in Nucl. Phys. A