Comparison of associated Higgs boson-radion and Higgs boson pair production processes

TL;DR

This paper compares the production processes of Higgs boson pairs and Higgs boson-radion pairs, highlighting the similarities and differences in their interactions within brane-world models, and introduces a rescaling factor for the triple Higgs coupling.

Contribution

It demonstrates that while Higgs and radion production processes are similar, a specific rescaling of the triple Higgs coupling is necessary for accurate modeling.

Findings

Radion interacts via the trace of the energy-momentum tensor.

The similarity in production processes requires rescaling the triple Higgs coupling.

A new factor $\xi$ is introduced for precise calculations.

Abstract

Many models, in particular, the brane-world models with two branes, predict the existence of the scalar radion, whose mass can be somewhat smaller than those of all the Kaluza-Klein modes of the graviton and Standard Model (SM) particles. Due to its origin the radion interacts with the trace of the energy-momentum tensor of the SM. The fermion part of the radion interaction Lagrangian is different from that for the SM Higgs boson due to the presence of additional terms playing a role for off-shell fermions. It was shown previously that for the case of the single radion and single Higgs boson production processes in association with an arbitrary number of SM gauge bosons all the contributions to the perturbative amplitudes appearing due to these additional terms were cancelled out making the processes similar up to a replacement of masses and overall coupling constants. For the case of the associated Higgs boson-radion and the Higgs boson pair production processes involving the SM gauge bosons the similarity property also takes place. However a detailed consideration shows that in this case it is not enough to replace simply the masses and the constants ($m_h \rightarrow m_r$ and $v \rightarrow \Lambda_r$). One should also rescale the triple Higgs coupling by the factor $\xi \equiv 1 + \frac{m_r^2 - m_h^2}{3m_h^2}$.