This paper describes a measurement of the Michel parameters, (Formula presented.), and the average (Formula presented.) helicity, (Formula presented.), in τ lepton decays together with the first measurement of the tensor coupling in the weak charged current. The (Formula presented.) pairs were produced at the LEP e+e− collider at CERN from 1992 through 1995 in the DELPHI detector. Assuming lepton universalityin the decays of the τ the measured values of the parameters were: (Formula presented.). The strength of the tensor coupling was measured to be κWτ = −0.029 ± 0.036 ± 0.018. The first error is statistical and the second error is systematic in all cases. The results are consistent with the V −A structure of the weak charged current in decays of the τ lepton.
ASJC Scopus subject areas
- Engineering (miscellaneous)
- Physics and Astronomy (miscellaneous)