The decay $\tau \to (\pi ,{\pi }^{\mathrm{\prime }}){\nu }_{\tau }$ in the Nambu - Jona-Lasinio model

In the Nambu - Jona-Lasinio model the decay widths $\tau \to (\pi, \pi’(1300)) \nu_{\tau}$werecalculated\mathrm{.}Forthecalculationofthedecaywidth$\tau \to \pi \nu_{\tau}$ the standard NJL model was used with taking into account the intermediate axial-vector meson and the extended Nambu - Jona-Lasinio model with the intermediate $a_1(1260)$ and $a_1^{\mathrm{\prime }}(1647)$ mesons. These results are in good agreement with each other. For the calculation of the decay width $\tau \to {\pi }^{\mathrm{\prime }}{\nu }_{\tau }$ extended Nambu - Jona-Lasinio model was used. The results are in satisfactory agreement with the experimental data. Numerical estimates for the constant $F_{\pi }$ and $F_{{\pi }^{\mathrm{\prime }}}$ are also in satisfactory agreement with both the experimental values for $F_{\pi }$ and the results obtained by calculations on the lattice.