Search for nonresonant pair production of highly energetic Higgs bosons decaying to bottom quarks

TL;DR

This paper reports a search for nonresonant Higgs boson pair production in proton-proton collisions, using advanced neural network techniques to identify boosted Higgs pairs decaying to bottom quarks, and sets new constraints on Higgs self-couplings.

Contribution

It introduces a novel analysis method using graph neural networks to identify boosted Higgs pairs and provides the first exclusion of the quartic VVHH coupling parameter $V$=0.

Findings

Excludes V=0 at 6.3 standard deviations

Constrains Higgs self-coupling strengths

Utilizes graph neural networks for boosted Higgs identification

Abstract

A search for nonresonant Higgs boson (H) pair production via gluon and vector boson (V) fusion is performed in the four-bottom-quark final state, using proton-proton collision data at 13 TeV corresponding to 138 fb$^{-1}$ collected by the CMS experiment at the LHC. The analysis targets Lorentz-boosted H pairs identified using a graph neural network. It constrains the strengths relative to the standard model of the H self-coupling and the quartic VVHH couplings, $\kappa_{2V}$, excluding $\kappa_{2V}$ = 0 for the first time, with a significance of 6.3 standard deviations when other H couplings are fixed to their standard model values.