Search for τ-lepton decays to seven or more pions with BABAR

We report the results of searches for several decay modes of the τ-lepton with ⩾7 pions in the final state using 207×106 τ-pairs collected with the BABAR detector. For the decays with 7 charged pions in the final state we find the following 90% CL upper limits: B(τ−→4π−3π+(π0)ντ)<3.0×10−7, B(τ−→4π−3π+ντ)<4.3×10−7, and B(τ−→4π−3π+π0ντ)<2.5×10−7. We also search for the decay τ−→3π−2π+2π0ντ and report a 90% CL upper limit of <3.4×10−6 for its branching fraction. Finally, we search for the exclusive final state τ−→2ωπ−ντ and find a 90% CL upper limit for its branching fraction of <5.4×10−7.