Abstract
In this work we study the Higgs boson decays into two photons and into one photon and one $Z$ gauge boson within the context of the non-linear Effective Field Theory called the Electroweak Chiral Lagrangian. We present a detailed computation of the corresponding amplitudes to one-loop level in the covariant $R_\xi$ gauges. We assume that the fermionic loop contributions are as in the Standard Model and focus here just in the computation of the bosonic loop contributions. Our renormalization program and the anatomy of the various contributions participating in the $R_\xi$ gauges are fully explored. With this present computation we demonstrate the gauge invariance of the EChL result, not only for the case of on-shell Higgs boson, but also for the most general and interesting case of off-shell Higgs boson. We finally analyse and conclude on the special relevance of the Goldstone boson loops, in good agreement with the expected chiral loops behaviour in Chiral Lagrangians. We perform a systematic comparison with the corresponding computation of the Standard Model in the $R_\xi$ gauges and with the previous EChL results in the unitary gauge. This work represents the first computation within the EChL of these Higgs observables to one-loop in the most general $R_\xi$ gauges and with a full renormalization program description, not yet fully explored in the previous literature and which is different to the most frequently used in the linear Effective Field Theory (SMEFT).
Highlights
After the discovery of the Higgs boson particle [1,2], a great effort has been done in exploring new aspects of the Higgs physics beyond the Standard Model (SM) with the tools of effective field theories (EFTs), both in the linear and in the nonlinear approach
The use of EFTs containing the Higgs boson particle and its interactions with all the SM particles, in a SUð3Þ × SUð2Þ × Uð1Þ gauge invariant way, is nowadays with no doubt, the best tool we have at hand to describe in a model-independent way the potential new Higgs physics from beyond the SM (BSM) dynamics
We have focused on the bosonic sector of the nonlinear EFT given by the electroweak chiral Lagrangian (EChL) which is the most appropriate one if the dynamics behind the EW symmetry breaking sector (EWSBS) is strongly interacting
Summary
After the discovery of the Higgs boson particle [1,2], a great effort has been done in exploring new aspects of the Higgs physics beyond the Standard Model (SM) with the tools of effective field theories (EFTs), both in the linear and in the nonlinear approach (for a review, see, e.g., [3]). We present an explicit and detailed computation of the one-loop amplitudes for the H → γγ and H → γZ decays within the EChL in the covariant Rξ gauges for the first time We consider both cases with the Higgs boson on shell and off shell and compare our results with the SM case. We should mention that other computations in the literature of these two Higgs boson decays within the context of EFT were done within the linear approach which, as we have said, involve different techniques, renormalization program, and counting rules than in the nonlinear case which we deal with here. The supplementary material needed for the computation, as the relevant Feynman rules (FRs), the chosen conventions for the loop integrals, and the preparation of the one-loop diagrams for the automated computation are summarized in the Appendices
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
