Off-shell structure of the anomalous Z and gamma self-couplings

Abstract

We establish the general off-shell structure of the three neutral gauge boson self-couplings V1*V2*V3*, with applications to the Z*Z*Z*, Z*Z*gamma*, gamma*gamma*Z* cases. New coupling forms appear which do not exist when two gauge bosons are on-shell. We give the contribution arising from a fermionic triangle loop. It covers both the standard model (SM) and possible new physics (NP) contributions like those arising in the MSSM. For what concerns NP contributions with a high scale, we discuss the validity of an effective Lagrangian involving a limited set of parameters. Finally we write the general expression of the V1*V2*V3*-vertex contribution to the e+e- to (f(bar) f)+(f'(bar) f') amplitude.

Comments: 37 pages, 7 figures and Addendum to Phys.Rev.D62,073012(2000) e-mail: renard@lpm.univ-montp2.fr