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.
Highlights
Interesting phenomena have been obsperffiffived in many experiments when the invariant energy s of the final system or its subsystem reaches the vicinity of 1.9 GeV
The aim of this work is to show that all such phenomena have their origins in the narrow ρ-like resonance ρð1900Þ, which has not found its way into the Particle Data Group (PDG)
Most of the data pointing to the role of the ρð1900Þ resonance represent the cross section for the eþe− annihilation into various final states
Summary
Interesting phenomena have been obsperffiffived in many experiments when the invariant energy s of the final system or its subsystem reaches the vicinity of 1.9 GeV (which is the energy very close to the NNthresholds). A later experiment, DM2, investigated the 3ðπþπ−Þ and 2ðπþπ−π0Þ final states, where the authors discovered a dip at about 1.9 GeV Their data have not been published in any journal. The existence of a narrow resonance with a mass close to the NNthreshold was suggested by the FENICE Collaboration while working at the Frascati eþe− storage ring ADONE from 1991–1993 They explained [12], in a paper published in 1996, that such a resonance interfering with the background given by broad resonances can generate a dip in the multihadronic cross section just below the NNthreshold, which they observed. The group working on the CMD-3 experiment claims that the behavior of these cross sections cannot be explained by the interference of any resonance amplitude with continuum They have not published their data yet, so we can neither confirm nor question their claim.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
