4 $\pi$ -decays of scalar and vector mesons

Abstract

Two different \(\bar{p}n\) annihilation modes, \(\bar{p}n\rightarrow\pi^{-}4\pi^{0}\) and \(\bar{p}n\rightarrow 2\pi^{-}2\pi^{0}\pi^{+}\), are used to study the 4\(\pi\)–decays of scalar and vector mesons. The data are dominated by 4\(\pi\) scalar isoscalar interactions. At least two states are needed, the \(f_{0}(1370)\) and the \(f_{0}(1500)\). The 4\(\pi\)–decay width of the \(f_{0}(1370)\) is more than 6 times larger than the sum of all observed partial decay widths to two pseudoscalar mesons. The state has important couplings to \((\pi\pi)_{\mathrm{S}}(\pi\pi)_{\mathrm{S}}\) and to \(\rho\rho\). The 4\(\pi\)-decays of the \(f_0\)(1500) represent about half of its total width. The \(\rho(1450)\) and the \(\rho(1700)\) are observed in several 4\(\pi\) decay modes. The ratio of the \(4\pi\) relative to the \(2\pi\) decay of the \(\rho(1450)\) is in contradiction to its proposed interpretation as a pure hybrid state but it suggests that it is not a pure \(2^{3}\rm S_{1}\)–state either. Our results favour the assignment of the \(\rho(1700)\) as \(^{3}\rm D_{1}\) state, its interpretation as \(3^{3}\rm S_{1}\)-state is less plausible.