We study the strange vector meson (K * ,K * ) dynamics in relativistic heavy-ion collisions based on the microscopic Parton-Hadron-String Dynamics (PHSD) transport approach which incorporates partonic and hadronic degrees-of-freedom, a phase transition from hadronic to partonic matter -Quark-Gluon-Plasma (QGP) -and a dynamical hadronization of quarks and antiquarks as well as final hadronic interactions. We investigate the role of in-medium effects on the K * ,K * meson dynamics by employing Breit-Wigner spectral functions for the K * 's with self-energies obtained from a self-consistent coupled-channel G-matrix approach. Furthermore, we confront the PHSD calculations with experimental data for p+p, Cu+Cu and Au+Au collisions at energies up to √ sNN = 200 GeV. Our analysis shows that at relativistic energies most of the final K * s (observed experimentally) are produced during the late hadronic phase, dominantly by the K + π → K * channel, such that the fraction of the K * s from the QGP is small and can hardly be reconstructed from the final observables. The influence of the in-medium effects on the K * dynamics at RHIC energies is rather modest due to their dominant production at low baryon densities (but high meson densities), however, it increases with decreasing beam energy. Moreover, we find that the additional cut on the invariant mass region of the K * further influences the shape and the height of the final spectra. This imposes severe constraints on the interpretation of the experimental results.

We investigate the in-medium properties of strange vector mesons (K * andK * ) in dense and hot nuclear matter based on chirally motivated models of the meson selfenergies. We parameterise medium effects as density or temperature dependent effective masses and widths, obtain the vector meson spectral functions within a Breit-Wigner prescription (as often used in transport simulations) and study whether such an approach can retain the essential features of full microscopic calculations. For µ B = 0 the medium corrections arise fromK * (K * )N scattering and thē K * (K * ) →K(K)π decay mode (accounting for in-mediumK(K) dynamics). We calculate the scattering contribution to the K * selfenergy based on the hidden local symmetry formalism for vector meson nucleon interactions, whereas for theK * selfenergy we implement recent results from a selfconsistent coupled-channel determination within the same approach. For µ B ≃ 0 and finite temperature we rely on a phenomenological approach for the kaon selfenergy in a hot pionic medium consistent with chiral symmetry, and evaluate theK * (K * ) →K(K)π decay width. The emergence of a mass shift at finite temperature is studied with a dispersion relation over the imaginary part of the vector meson selfenergy.

We investigate the possibility of probing the hot and dense nuclear matter -created in relativistic heavy-ion collisions (HIC) -with strange vector mesons (K * ,K * ). Our analysis is based on the non-equilibrium Parton-Hadron-String Dynamics (PHSD) transport approach which incorporates partonic and hadronic degrees-of-freedom and describes the full dynamics of HIC on a microscopic level -starting from the primary nucleon-nucleon collisions to the formation of the strongly interacting Quark-Gluon-Plasma (QGP), followed by dynamical hadronization of (anti-)quarks as well as final hadronic elastic and inelastic interactions. This allows to study the K * andK * meson formation from the QGP as well as the in-medium effects related to the modification of their spectral properties during the propagation through the dense and hot hadronic environment in the expansion phase. We employ relativistic Breit-Wigner spectral functions for the K *