Nuclear medium effects on invariant mass spectra of hadrons decaying in nuclei

Effects of nuclear medium on invariant masses of in-medium hadrons as reconstructed from their decay particles alone (here called quasi invariant masses) are examined. Such “inclusive” invariant masses are related to the average potential energies, and thus are not identified as medium-modified hadronic masses. Furthermore, a significant fraction of in-medium hadrons is subject to decay in correlation with surrounding nucleons, producing a broad pseudo peak at a lower mass in a quasi invariant mass spectrum, as calculated for ρ meson decays in high density medium and for proton decays in 16O.