Tests for tauʹs charged-current structure

The Lorentz structure of the tau leptonʹs charged-current can almost be completely determined by use of stage-two spin-correlation functions for the {ϱ−, ϱ+} and {a1−, a1+} decay modes. It is possible to test for “(V − A) + something” structure in the Jchargedlepton current, so as to boundthe scales Λ for “new physics” such as arising from tau weak magnetism, weak electricity and/or second-class currents. In practice, only limited information can be obtained from the τ → πν channels.