The NNbar and multihadron production at the threshold at VEPP2000

¹ Budker Institute of Nuclear Physics, SB RAS, Novosibirsk, 630090, Russia
² Novosibirsk State University, Novosibirsk, 630090, Russia
³ Novosibirsk State Technical University, Novosibirsk, 630092, Russia
⁴ University of Victoria, Victoria, BC, Canada V8W 3P6
⁵ Lebedev Physical Institute RAS, Moscow, 119333, Russia

^* e-mail: solodov@inp.nsk.su

Published online: 17 June 2019

Abstract

A study of hadron production at the nucleon-antinucleon threshold has been performed with the CMD-3 detector at the VEPP-2000 e⁺e⁻ collider. A very fast rise with an about 1 MeV width has been observed in the e⁺e⁻→ pp̅ cross section. A sharp drop in the e⁺ e⁻→ 3(π⁺π⁻) cross section has been con?rmed and found to have a width of less than 2 MeV, in agreement with the observed fast rise of the e⁺e⁻→ pp̅ cross section. For the ?rst time a similar sharp drop is demonstrated in the e⁺e⁻→ K⁺ K⁻π⁺π⁻ cross section. The behavior of the e⁺e⁻→ 3(π⁺ π⁻), K⁺ K⁻π⁺π⁻ cross sections cannot be explained by an interference of any resonance amplitude with continuum, therefore this phenomenon cannot be due to a narrow near-threshold resonance. No such structure has been observed in the e⁺e⁻→ 2(π⁺π⁻) cross section.