The branching fraction of the ${\tau }^{-}\to 3h^{-}2h^{+}{\nu }_{\tau }$ decay ($h=\pi ,K$) is measured with the BABAR detector to be $(8.56\pm 0.05\pm 0.42)\times {10}^{-4}$, where the first error is statistical and the second systematic. The observed structure of this decay is significantly different from the phase space prediction, with the $\rho$ resonance playing a strong role. The decay ${\tau }^{-}\to f_1(1285){\pi }^{-}{\nu }_{\tau }$, with the $f_1(1285)$ meson decaying to four charged pions, is observed and the branching fraction is measured to be $(3.9\pm 0.7\pm 0.5)\times {10}^{-4}$.

• Received 3 May 2005

DOI:https://doi.org/10.1103/PhysRevD.72.072001