Decays τ → ππην_τ and τ → πηην_τ in the extended Nambu–Jona-Lasinio model

In the framework of the extended Nambu–Jona-Lasinio model, the processes τ → ππη(η′)ν_τ and τ → πηη(η′)ν_τ are considered taking into account mesons in the ground and first radially excited intermediate states. It is shown that in the processes τ → ππη(η′)ν_τ the vector channel is dominant, and in the processes τ → πηη(η′)ν_τ the main contribution is given by the axial-vector channel. The scalar meson a₀ plays a dominant role in processes with two η mesons in the final state. The significance of the relative phase between the ground and first radially excited states for these processes is shown. The obtained results for the τ → ππην_τ process are in satisfactory agreement with the recent experimental data from BaBar and CMD-3, which differ from the averaged values given in the PDG tables.