2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/42408We point out that a commonly used parameterization form to describe the $σ$ resonance is problematic by introducing a spurious singularity below two particle threshold, on the second sheet. The spurious singularity violates chiral symmetry and leads to sizable contribution when the resonance is light and broad -- as what happens to the $σ$ resonance, hence must be removed.A mistaken remark concerning the property of deeply bounded resonances isremoved and correctedHigh Energy Physics - Phenomenologytext