General one-loop contributions to the decay $H\rightarrow \nu_l\bar{\nu}_l\gamma$

Khiem Hong Phan,Le Tho Hue,Dzung Tri Tran

doi:10.1093/ptep/ptab121

Abstract

Abstract General one-loop contributions to the decay amplitudes $H\rightarrow \nu_l\bar{\nu}_l\gamma$ are presented, considering all possible contributions of additional heavy vector gauge bosons, fermions, and charged (and also neutral) scalar particles appearing in the loop diagrams. Moreover, the results can be applied directly when extra neutrinos (apart from three ones in the standard model) are taken into account in final states. Analytic results are expressed in terms of Passarino–Veltman scalar functions which can be evaluated numerically using $\texttt{LoopTools}$. In the standard model framework, these analytical results are generated and cross-checked with previous computations. We find that our results are well consistent with these computations. Within the standard model limit, phenomenological results for the decay channels are also studied using the present input parameters at the Large Hadron Collider. Lastly, the calculation is also applied to the Two Higgs Doublet Model framework as another example.

Highlights

Searching for all decay modes of the standard model-like (SM-like) Higgs boson is one of the main purposes of the High Luminosity Large Hadron Collider (HL-LHC) [1,2] as well as Future Lepton Colliders [3], because the partial decay widths of the Higgs boson contain an important information for testing the nature of Higgs sector
The results are valid for many beyond the standard models (BSM); new heavy vector bosons, fermions, and scalar particles predicted by these models are considered in the loop diagrams
We have presented analytic formulas for all possible one-loop contributions to the SM-like Higgs decay H → νlνlγ that are valid in many BSMs

Summary

Introduction

Searching for all decay modes of the standard model-like (SM-like) Higgs boson is one of the main purposes of the High Luminosity Large Hadron Collider (HL-LHC) [1,2] as well as Future Lepton Colliders [3], because the partial decay widths of the Higgs boson contain an important information for testing the nature of Higgs sector. Among the Higgs decay modes, the channels of H → invisible particles [4,5,6,7,8,9,10] and H → γ plus invisible particles [11,12] are greatly of interest, for the following reasons These decay processes can be measured at the LHC [4,5,6,8,11,12]. The results are valid for many BSMs; new heavy vector bosons, fermions, and scalar particles predicted by these models are considered in the loop diagrams. The results of this work can be applied to calculate one-loop contributions of new particles predicted by well-known BSMs constructed previously, for example, many popular SM extensions that include only new charged scalars such as THDM [18]. Checks for the calculation are discussed and we briefly review THDM in the appendices

Calculation

Method

One-loop box diagrams

Two Higgs Doublet Model case

Conclusions