Search for Second-Class Currents in tau- -> omega pi- nu_tau
  We report on an analysis of $\tau^-$ decaying into $\omega\pi^-\nu_\tau$ with $\omega\to\pi^+\pi^-\pi^0$ using data containing nearly 320 million tau pairs collected with the BABAR detector at the PEP-II asymmetric energy $B$-Factory. We find no evidence for second-class currents and set an upper limit at 0.69% at a 90% confidence level for the ratio of second- to first-class currents. 
The BABAR Collaboration: B. Aubert, et al