Radiative corrections to decays of the 125 GeV Higgs boson in the complex Higgs triplet model

TL;DR

This paper calculates radiative corrections to the 125 GeV Higgs boson decays in a complex triplet Higgs model, revealing potential deviations from the Standard Model predictions that could be observed at future colliders.

Contribution

It provides a comprehensive calculation of one-loop radiative corrections to Higgs decays in the complex triplet model, including gauge dependence removal and higher-order QCD effects.

Findings

Decay rates can be several percent larger than SM predictions.

Deviations in $h\to \gamma\gamma$ and Higgs self-coupling can reach -20% and 100%.

Distinct deviation patterns from other extended Higgs models.

Abstract

The extension of the Higgs sector with an additional complex triplet field is often considered for generating the neutrino mass by the Type-II seesaw mechanism. Such an extension generally predicts $\rho\neq1$, where $\rho$ is the electroweak rho parameter at the tree level, so that the renormalization of the electroweak parameters is different from models like the standard model (SM) and two Higgs doublet models. In this paper, we present a full set of radiative corrections to decays of the 125 GeV Higgs boson ($h$) in this model. One-loop contributions of the extra Higgs bosons as well as SM fermions and gauge bosons to the decay rates of $h$ are calculated in the on-shell scheme. Gauge dependence appearing in the counter terms of mixing angles is eliminated by the pinch technique. Higher-order QCD corrections are also implemented. We find that the decay rates can significantly deviate from the predictions in the SM and other extensions such as the two Higgs doublet models and the singlet model. For example, the decay rates of $h\to WW^\ast$ and $h\to ZZ^\ast$ can be a few percent larger than the SM value under current experimental and theoretical constraints. In this case, deviations in $h\to \gamma\gamma$ and Higgs self-coupling can reach about $-20\%$ and $100\%$, respectively. The pattern of the deviations is different from the other extended Higgs models. These characteristic predictions are expected to be detected at the High-Luminosity LHC or future Higgs factories.