Phi Meson Propagation and Decay at Finite Temperature

We study spectral properties of the phi meson at finite temperature using an effective Lagrangian together with finite-temperature field theory as a basis for modeling. General field-theoretic arguments are then used to establish the lifetime of the phi in hot hadronic matter. We find from the model, and we therefore propose a scenario in which, the phi decays inside the fireball. Early decays into $\mu^{+}\mu^{-}$ occur at high temperature while measurable hadronic decays into $K^{+}K^{-}$ (not suffering rescattering) occur at freezeout, where flow could be substantial. These results provide a consistent picture, if not possible interpretation of the NA49 and NA50 data from CERN.