Common explanation of the behavior of some $e^{+}{e}^{-}$ annihilation processes around $\sqrt{s}$ = 1.9 GeV

Abstract

We show that the behavior of the excitation curves of some $e^{+}{e}^{-}$ annihilation processes close to the nucleon-antinucleon threshold can be explained either by the $\rho (1900)$ resonance itself or by its interference with other resonances. Besides the six-pion annihilation and the $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}$ and $e^{+}{e}^{-}\to \Phi {\pi }^0$ processes, we also analyze the final states $\eta {\pi }^{+}{\pi }^{-}$, $K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}{\pi }^0$, and $K^{+}{K}^{-}{\pi }^0{\pi }^0$, the behavior of which around 1.6 GeV has not yet attracted attention. Analysis of the data on the $e^{+}{e}^{-}\to p\bar{p}$ and $e^{+}{e}^{-}\to n\bar{n}$ reactions clearly shows that the $\rho (1900)$ resides above the $n\bar{n}$ threshold.

Comments: 14 pages, 16 figures; The journal version is expanded by Appendix containing an analytic formula for the $e^{+}{e}^{-}\to \Phi {\pi }^0$ cross section