The strangest non-strange meson is not so strange after all

Abstract

With its large decay width and huge non-resonant background, the lowest-mass strangeness-zero \(\pi \pi\) resonance \(f_0(500)\) is rather strange. Since the lightest \(\pi N\) resonance \(\Delta(1232)\) has an unusually large background too, we analyze these two and a few other meson and baryon resonances, as well as the Z boson, to show that the background is generally smaller the farther the resonance is from the threshold. This result indicates that the \(f_0(500)\) has a very large residue phase, a substantially larger Breit-Wigner mass, and that it is a simple Breit-Wigner resonance after all.