Abstract
We examine trilinear and quartic anomalous gauge couplings (AGCs) generated in composite Higgs models and models with warped extra dimensions. We first revisit the SU(2)_L x U(1)_Y effective Lagrangian and derive the charged and two-photon neutral AGCs. We derive the general perturbative contributions to the pure field-strength operators from spin 0, 1/2, 1 resonances by means of the heat kernel method. In the composite Higgs framework, we derive the pattern of expected deviations from typical SO(N) embeddings of the light composite top partner. We then study a generic warped extra dimension framework with AdS_5 background, recasting in few parameters the features of models relevant for AGCs. We also present a detailed study of the latest bounds from electroweak and Higgs precision observables, with and without brane kinetic terms. For vanishing brane kinetic terms, we find that the S and T parameters exclude KK gauge modes of the RS custodial [non-custodial] scenario below 7.7 [14.7] TeV, for a brane Higgs and below 6.6 [8.1] TeV for a Pseudo Nambu-Goldstone Higgs, at 95% CL. These constraints can be relaxed in presence of brane kinetic terms. The leading AGCs are probing the KK gravitons and the KK modes of bulk gauge fields in parts of the parameter space. In these scenarios, the future CMS and ATLAS forward proton detectors could be sensitive to the effect of KK gravitons in the multi-TeV mass range.
Highlights
Higgs framework, we derive the pattern of expected deviations from typical SO(N ) embeddings of the light composite top partner
We remark that the new indirect bounds for vanishing brane kinetic terms (BKTs) derived above most likely push the Kaluza Klein (KK) resonances beyond the reach of the LHC, unless some mechanism suppresses the coupling of the Higgs field to electroweak KK modes, for instance by modifying the geometry in the IR [33,34,35], reducing in particular the T parameter in non-custodial models [20, 36, 37]
Anomalous gauge couplings of the Standard Model constitute a rich source of information about the new physics potentially lying above the TeV scale
Summary
First we define the set of higher dimensional operators entering the effective Lagrangian eq (1.2). The complete Lagrangian describing anomalous gauge couplings in the broken phase, needed for phenomenology and experimental studies, will be derived . Our dimension six basis is defined in such a way that (in renormalizable theories) the operators OF F , OW 3 are only generated pertubatively at the loop level while the other ones can potentially be generated at treelevel. This convenient basis has been already used in [9], is discussed more formally in [10], and is consistent with the general basis presented in [11]. We display below only the operators which will feed into anomalous gauge couplings, or will be closely related to their study. We limit ourselves to two-photon QGCs, such that by gauge invariance the operators O1,2 cannot contribute
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