We extend our recent study of dilepton invariant-mass spectra from the decays of ρ mesons produced by photon reactions off nuclei. We specifically focus on experimental spectra as recently measured by the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility using carbon and iron nuclei. Building on our earlier work, we broaden our description to a larger set of observables to identify sensitivities to the medium effects predicted by microscopic calculations of the ρ spectral function. We compute mass spectra for several target nuclei and study the spectral shape as a function of the three-momentum of the outgoing lepton pair. We also compute the so-called nuclear transparency ratio, which provides an alternative means (and thus consistency check) of estimating the ρ width in the cold nuclear medium.

We reanalyze the dissociation process of the J/ψ by π and ρ mesons into D +D, D * +D, D +D * , and D * +D * within a meson exchange model. In addition to the dissociation mechanisms considered in the literature, we consider anomalous parity interactions, whose couplings are constrained by heavy quark spin symmetry and phenomenology. This opens new dissociation channels and adds new diagrams in the previously considered processes. Compared to the previous results, we find that these new additions have only a minor effect on the ρ + J/ψ total inelastic cross section, but reduce the one for π + J/ψ by about 50 % near the threshold.

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We study the photoproduction of K * (892) vector meson from both the charged and neutral reactions, γp → K * + Λ and γn → K * 0 Λ. The production mechanisms that we consider include t-channel K * , K, κ exchanges, s-channel nucleon diagram, and u-channel Λ, Σ, Σ * diagrams. These could constitute important backgrounds for future investigation of "missing" resonances that can be searched for especially in these reactions. The t-channel K meson exchange is found to dominate both reactions. The total and differential cross sections are presented together with some spin asymmetries.