Manifestation of kaonium in the e+e−→K+K− process

Possible manifestation of the 2p pionium in particle physics processes

“…PIONIUM IN THE e + e − → π + π − PROCESS Recently, we have succeeded [12] in locating 2p kaonium as a bound-state pole in the amplitude of the e + e − → K + K − process. The pole corresponding to 2p kaonium lies on the real axis in the complex s-plane below the K + K − threshold.…”

“…Our aim here is to find a pole in e + e − → π + π − amplitude that would correspond to 2p pionium by fitting the data on the e + e − → π + π − cross section. Our experience with 2p kaonium shows that the crucial role in discovering the bound-state pole, which lies below the reaction threshold, is played by the cross section data at low energies, as close to the threshold as possible [12]. Unfortunately, almost all e + e − → π + π − experiments have concentrated on the ρ/ω region or on energies above φ(1020).…”