Search for τ−→4π−3π+(π0)ντ Decays

A search for the decay of the τ lepton to seven charged pions and at most one π0 was performed using the BABAR detector at the PEP-II e+e− collider. The analysis uses data recorded on and near the ϒ(4S) resonance between 1999 and 2003, a total of 124.3 fb−1. We observe 7 events with an expected background of 11.9 ± 2.2 events and calculate a preliminary upper limit of BR(τ−→4π−3π+(π0)ντ<2.7×10−7 at 90 % CL. This is a significant improvement over the previous limit established by the CLEO Collaboration.