Speaker
Description
Since dileptons can leave the dense phase of a reaction without distortion, their observation may allow us to observe in\,-\,medium effects on mesons produced in hadron induced reaction. The masses of the low lying charmonium states, the $J/\Psi$, $\Psi(3686)$, and $\Psi(3770)$ are shifted downwards due to the second order Stark effect. In hadron + \text{Au}$ collisions at $6-20$~GeV we study their in\,-\,medium propagation. The time evolution of the spectral functions of these charmonium states is studied with a BUU type transport model. We show that their in\,-\,medium mass shift can be observed in the dilepton spectrum, therefore, we may gain information about the magnitude of the gluon condensate in nuclear matter. This measurement could be performed at JPARC or at the upcoming PANDA experiment at FAIR. Very interesting in-medium effect on $\rho$ and $\omega$ mesons can be observed by studying their interference contributing to the dilepton spectra in difference $pi^+$ and $\pi^-$ induced reactions at 1-2 GeV pion beam energies. This may be observed in JPARC.
