ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2005, vol. 72, p. 1-8
Search for the decay τ-→4π-3π+(π0)ντ
A search for the decay of the τ lepton to seven charged pions and one or zero π0 mesons was performed using the BABAR detector at the PEP-II asymmetric-energy e+e- collider. The analysis uses 232.2fb-1 of data at center-of-mass energies on or near the Υ(4S) resonance. We observe 24 events with an expected background of 21.6±1.3 events. Without evidence for a signal, we calculate an upper limit of B(τ-→4π-3π+(π0) ντ)<3.0×10-7 at 90% confidence level. This is an improvement by nearly an order of magnitude over the previously established limit. In addition, we set upper limits for the exclusive decays τ-→4π-3π+ντ and τ-→4π-3π+π0ντ. © 2005 The American Physical Society.