Study of high-multiplicity three-prong and five-prong τ decays at BABAR

We present measurements of the branching fractions of three-prong and five-prong τ decay modes using a sample of 430 million τ lepton pairs, corresponding to an integrated luminosity of 468 fb − 1 , collected with the BABAR detector at the PEP-II asymmetric-energy e + e − storage rings at SLAC National Accelerator Laboratory. The τ − → ( 3 π ) − η ν τ , τ − → ( 3 π ) − ω ν τ , and τ − → π − f 1 ( 1285 ) ν τ branching fractions are presented, as well as a new limit on the branching fraction of the second-class current decay τ − → π − η ′ ( 958 ) ν τ . We search for the decay mode τ − → K − η ′ ( 958 ) ν τ and for five-prong decay modes with kaons, and place the first upper limits on their branching fractions.