Perspectives of scalar- and vector-meson production in hadron-nucleus reactions

The production and decay of vector mesons ($\rho, \omega$) in $pA$ reactions at COSY energies is studied with particular emphasis on their in-medium spectral functions. It is explored within transport calculations, if hadronic in-medium decays like $\pi^+\pi^-$ or $\pi^0 \gamma$ might provide complementary information to their dilepton ($e^+e^-$) decays. Whereas the $\pi^+ \pi^-$ signal from the $\rho$-meson is found to be strongly distorted by pion rescattering, the $\omega$-meson Dalitz decay to $\pi^0 \gamma$ appears promising even for more heavy nuclei. The perspectives of scalar meson ($f_0, a_0$) production in $pp$ reactions are investigated within a boson-exchange model indicating that the $f_0$-meson might hardly be detected in these collisions in the $K \bar{K}$ or $\pi \pi$ decay channels whereas the exclusive channel $pp \to d a_0^+$ looks very promising.