Search for the 7-prong tau decay

A long standing puzzle in $\tau$ lepton decays is the apparent suppression of decays with seven or more hadrons in the final state. We present results on the search for the $\tau$ decay into seven charged pions with and without a $\pi^{0}$, and a neutrino. Our data sample, a total of 232.2 fb$^{-1}$ on and near the $\Upsilon(4S)$-resonance, was collected using the BaBar detector at the PEP-II asymmetric $e^+e^-$-collider at the Stanford Linear Accelerator Center. The results from this analysis are a significant improvement over the previously established upper limit on the decay branching ratio.