Left: The effective phase shift extracted from the coupled-channel model, compared to the result of the model in Ref. . For the latter, the decomposition of its components: \(\sigma (500)\), \(f_0(980)\) and a repulsive background, is also displayed. Right: The effective spectral function computed via Eq. (3). Also shown are the results of a (normalized) energy-dependent Breit–Wigner spectral functions based on the model in Ref. , and the \(I=2\) result computed using the experimental data in Ref.