Stefan Leupold

HADRONS IN STRONGLY INTERACTING MATTER

We review the current status of theories and experiments aiming at an understanding and a determination of the properties of light vector and scalar mesons inside strongly interacting hadronic matter. Starting from a discussion of the relevant symmetries of QCD and their connection with the hadronic description through QCD sum rules we then discuss hadronic models used to calculate the in-medium self-energies of hadrons and their spectral functions. The difficulties to link these calculated properties to actual observables are emphasized. Finally, we review in detail all the running experiments searching for in-medium changes of vector and scalar mesons, both with relativistic heavy-ion reactions as well as with elementary reactions on (cold) nuclei. Inconsistencies among experimental results are discussed. While almost all experiments observe a considerable broadening of vector mesons inside the nuclear medium, no evidence for mass changes is observed in the majority of the experiments.

Electromagnetic transition form factors of light vector mesons

Abstract The decays of narrow light vector mesons into pseudoscalar mesons and dileptons are calculated to leading order in a recently proposed scheme which treats pseudoscalar and vector mesons on equal footing. Since all required parameters have been determined by other reactions the presented approach gains predictive power for the considered processes. The decay of the ω -meson into pion and dimuon agrees reasonably well with the available experimental data concerning form factor, single-differential decay width and partial decay width. As well do the partial decay width of the ω -meson into a pion and a dielectron and of the ϕ -meson into an η -meson and a dielectron. The decay properties of the ω -meson into η -meson and dimuon or dielectron and of the ϕ -meson into η -meson and dimuon are predicted.

Dispersive analysis of the pion transition form factor

We analyze the pion transition form factor using dispersion theory. We calculate the singly-virtual form factor in the time-like region based on data for the

On QCD sum rules for vector mesons in nuclear medium

e^+e^-\rightarrow 3\pi

Equilibration and relaxation times at the chiral phase transition including reheating

e+e-→3π cross section, generalizing previous studies on

The impact of dissipation and noise on fluctuations in chiral fluid dynamics

\omega ,\phi \rightarrow 3\pi