Bounds on Higgs and Gauge--Boson Interactions from LEP2 Data

Abstract

We derive bounds on Higgs and gauge--boson anomalous interactions using the LEP2 data on the production of three photons and photon pairs in association with hadrons. In the framework of $SU(2)_L \otimes U(1)_Y$ effective Lagrangians, we examine all dimension--six operators that lead to anomalous Higgs interactions involving $γ$ and $Z$. The search for Higgs boson decaying to $γγ$ pairs allow us to obtain constrains on these anomalous couplings that are comparable with the ones originating from the analyses of $p\bar{p}$ collisions at the Tevatron. Our results also show that if the coefficients of all ``blind'' operators are assumed to have same magnitude, the indirect constraints on the anomalous couplings obtained from this analyses, for Higgs masses $M_H \lesssim$ 140 GeV, are more restrictive than the ones coming from the $W^+W^-$ production.