The lightest scalar meson in a simple approach

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We study basic properties of scalar hadronic resonances within a quantum field theoretical toy model. In particular, we focus on the spectral function, the mass and the decay width of the resonance f₀(500). In this work, this meson is understood as a seed state in an effective Lagrangian which couples to pions. With such a setup we use the position of the pole on the second Riemann sheet in order to obtain its spectral function. We confirm that f₀(500) cannot be described by an ordinary Breit--Wigner function, and that a more complicated structure is needed.