Production of $HHH$ and $HHV(V=\gamma,Z)$ at the hadron colliders

TL;DR

This paper calculates the production rates and distributions of triple Higgs and Higgs-Z boson processes at hadron colliders within the Standard Model, including higher-order QCD contributions and potential new physics effects from anomalous couplings.

Contribution

It provides the first detailed calculation of gluon-gluon fusion contributions to $pp o HHH$ and $pp o HHZ$, including NNLO effects and anomalous coupling impacts.

Findings

NNLO gluon fusion contributions can be comparable to NLO at LHC energies.

Anomalous couplings can significantly enhance cross sections.

Triple Higgs production is highly sensitive to Higgs self-coupling deviations.

Abstract

We consider the production of two Higgs bosons in association with a gauge boson or another Higgs boson at the hadron colliders. We compute the cross sections and distributions for the processes $ p p \to H H H $ and $H H Z$ within the standard model. In particular, we compute the gluon-gluon fusion one-loop contributions mediated via heavy quarks in the loop. It is the leading order contribution to $ p p \to H H H $ process. To the process $ p p \to H H Z $, it is next-to-next-to-leading-order (NNLO) contribution in QCD coupling. We also compare this contribution to the next-to-leading-order (NLO) QCD contribution to this process. The NNLO contribution can be similar to NLO contribution at the Large Hadron Collider (LHC), and significantly more at higher center-of-mass energy machines. We also study new physics effects in these processes by considering $ttH, HHH, HHHH, HZZ$, and $HHZZ$ interactions as anomalous. The anomalous couplings can enhance the cross sections significantly. The $gg \to HHH$ process is specially sensitive to anomalous trilinear Higgs boson self-coupling. For the $gg \to HHZ$ process, there is some modest dependence on anomalous $HZZ$ couplings.