The decay $τ\to 3πν_τ$ and axial-vector meson $a_1$ in the NJL model
The branching fractions of $τ\to π^+ π^-π^- ν_τ$ and $τ\to π^- 2π^0ν_τ$ are calculated within the chiral NJL model. Features of the axial-vector $a_1$ meson which plays an important role in describing the $τ$ decays are discussed. Permissible values for the mass and width of the $a_1$ meson are considered in accordance with the latest experiments.
hep-ph↗