Bounds on $g_5^Z$ from Precision LEP Measurements

Abstract

The parity violating but CP conserving anomalous three-gauge-boson coupling $g_5^Z$ induces a universal contribution to the left-handed coupling of the $Z$ boson to fermions. We find that the LEP measurements of the partial $Z$ widths and lepton forward-backward asymmetries are sufficiently precise to place a bound of order $|g_5^Z|$ less than $\sim 10\%$. This bound is significantly better than what can be obtained at present from rare $K$ and $B$ meson decays.

Comments: Phys. Lett. B333 (1994) 207. A few minor errors in the table are corrected and updated experimental and theoretical numbers are used. The conclusions are unchanged. These changes will appear in an erratum to the published paper