The decay $\tau \to K^{*-}(892) \eta \nu_{\tau}$ in the NJL model

The decay width $\tau \to K^{*-}(892) \eta \nu_{\tau}$ was calculated in the Nambu--Jona-Lasinio model. Four channels were taken into account: the contact channel (the final states are directly producted from lepton current without any intermediate meson states), the axial-vector channel with two intermediate physical states $K_{1}(1270)$ and $K_{1}(1400)$, the vector channel with intermediate $K^{*}(892)$ meson and the pseudoscalar channel with intermediate $K$ meson. It is shown that the first two channels give the dominant contribution to the decay width. Of the remaining two channels, the pseudoscalar channel plays a more prominent role. The final result is in satisfactory agreement with experimental data. Prediction for the differential decay width is presented.

M. K. Volkov, A. A. Pivovarov, K. Nurlan · 2019