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Moment analysis of the phi-meson spectral function in vacuum and nuclear matter
In this seminar, the results of our moment analysis of the phi-meson spectral function in vacuum and in nuclear matter will be presented. Combining an effective field theory treatment, based on kaonic degrees of freedom, with finite-energy QCD sum rules, we show that the spectral density in the vacuum is strongly constrained by a recent accurate measurement of the e^+ e^- to K^+ K^- cross section. In nuclear matter the phi spectrum is modified by interactions of the decay kaons with the surrounding nuclear medium, leading to a significant broadening and an asymmetric deformation of the \phi meson peak. We demonstrate that both in vacuum and nuclear matter, the first two moments of the spectral function are compatible with finite-energy QCD sum rules.