Thee+e−→η(η′)2πprocess in the extended Nambu–Jona-Lasinio model

Abstract

Process of electron-positron annihilation into η(η ′ )2π is described within the extended NJL model in the energy range up to about 2 GeV. Contributions of intermediate vector mesons ρ(770) and ρ(1450) are taken into account. Results for the η2π channel are found to be in a reasonable agreement with experimental data. Predictions for production of η ′ 2π are given. The corresponding estimations for decays τ → η(η ′ )2πν are given in Appendix.

Review of e+e− → π+π−η

“…Comparison of the extended NJL model prediction with the BaBar experiment data [7]. The figure is taken from [11].…”

“…The reaction (1) was first observed at the end of 70's in the DM1 experiment [1] and since that time it was studied by Orsay [2], Novosibirsk [3][4][5][6] groups and by the BaBar collaboration [7,8]. From a theoretical point of view the ηππ production in the e + e − -annihilation and τ-lepton decay was discussed in [4,[9][10][11] using different approaches.…”

“…The reaction (1) within the extended nonlocal version of the Nambu-Jona-Lasinio (NJL) model studied in [11,12] and the corresponding Feynman diagrams are shown in Fig. 5.…”

“…The VMD approach could be directly obtained from the NJL model by taking into account only the diagram with the triangle loops. Precise formulae for the cross section can be found in Section III of [11]. Numerical values of the model parameters are fixed in Eq.…”

“…Numerical values of the model parameters are fixed in Eq. (4) of [11] whereas for the resonance masses and widths their PDG values are chosen. The comparison with the BaBar data is presented in Fig.…”