Low energy effects of new interactions in the electroweak boson sector

Novel strong interactions in the electroweak bosonic sector are expected to induce effective interactions between the Higgs doublet field and the electroweak gauge bosons which lead to anomalous $\mathrm{WWZ}$ and $\mathrm{WW}\ensuremath{\gamma}$ vertices once the Higgs field acquires a vacuum expectation value. Using a linear realization of the Goldstone bosons, we consider a complete set of dimension-six operators which are SU(2)\ifmmode\times\else\texttimes\fi{}U(1) gauge invariant and conserve $C$ and $P$. This approach allows us to study effects of new physics which originates above 1 TeV and the Higgs boson mass dependence of the results can be investigated. Four of the dimension-six operators affect low energy and present CERN LEP experiments at the tree level. Another five influence neutral and charged current experiments at the one-loop level and three of these lead to anomalous $\mathrm{WWZ}$ and $\mathrm{WW}\ensuremath{\gamma}$ vertices. Their loop contributions are at most logarithmically divergent, and these logarithmic divergences can be understood as renormalizations of the four operators which contribute at the tree level. Constraints on the remaining five operators can be obtained if one assumes the absence of cancellations between the tree level and one-loop contributions. The resulting bounds on anomalous triple gauge boson couplins are modest, which emphasizes the importance of direct measurements of the triple gauge boson vertices, e.g., in ${W}^{+}{W}^{\ensuremath{-}}$ production at LEP II.

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