Anomalous Gauge Boson Interactions

Abstract

We discuss the direct measurement of the trilinear vector boson couplings in present and future collider experiments. The major goals of such experiments will be the confirmation of the Standard Model (SM) predictions and the search for signals of new physics. We review our current theoretical understanding of anomalous trilinear gauge-boson self interactions. If the energy scale of the new physics is ∼ 1 TeV, these low energy anomalous couplings are expected to be no larger than O(10 −2 ).Constraints from high precision measurements at LEP and low energy charged and neutral current processes are critically reviewed.

New Physics Effects in Rare Z Decays

“…It was also realized long time ago that the production of single photons at LEP-1 energies constitute a process which is most sensitive to anomalous ZZγ couplings due to the large branching ratio for the Z →νν mode and the absence of background from final state radiation [18,19]. Since the L3 and DELPHI Collaborations found that the level of energetic single-photon events is consistent with what is expected in the SM [20], from the limit (5) it is possible to derive upper bounds on the ZZγ coupling.…”

“…In the SM they vanish a tree level and one-loop effects are of the order of 10 −10 [21]. These couplings have not been measured with good precision [18,19,20] and any deviation from the SM prediction may be thus associated with physics beyond the SM.…”

Probing trilinear gauge boson interactions via single electroweak gauge boson production at the CERN LHC

“…The study of these interactions can either lead to an additional confirmation of the model or give some hint on the existence of new phenomena at a higher scale [1]. The triple gauge-boson vertices (TGV's) have been probed directly at the Tevatron [2] and LEP [3,4] through the production of vector-boson pairs and the experimental results agree with the SM predictions within O(10%); see Table I.…”

“…[8] for the SSC energy but had not been discussed in the context of the LHC. A potential drawback of the single gauge boson production as a test of electroweak vertices at the LHC energies is the large expected background from higher order QCD corrections to the Drell-Yan process 1 . However, it has been recently proved in the case of Higgs production [10] that these backgrounds are under control due to the presence of two very energetic forward jets.…”

Anomalous triple gauge boson couplings in ZZ production at the LHC and the role of Z boson polarizations

“…The anomalous neutral triple gauge boson couplings in Eq. (1) have been widely studied in the literature for various colliders: in e + e − collider [7,9,[17][18][19][21][22][23][24][25], eγ collider [10,15,16], γγ collider [20], hadron collider [8,12,14,26,27] and both e + e − and hadron collider [6,11,13]. On the experimental side, the anomalous Lagrangian in Eq.…”