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Studying the Higgs Potential at the e+e- Linear Collider

Marco Battaglia, Eduard Boos, Weiming Yao

TL;DR

This paper addresses the problem of probing the shape of the Higgs potential by measuring the triple Higgs self-coupling $g_{HHH}$ at an $e^+e^-$ linear collider. It analyzes two production channels, $e^+e^- \to HHZ$ and $e^+e^- \to HH\nu\bar{\nu}$, at TeV-class and multi-TeV energies, using a full simulation chain and observables such as the $M_{HH}$ distribution and the angular variable $|\,\cos\theta^*|$ to mitigate dilution from non-$g_{HHH}$ diagrams. The study finds that at a 500 GeV collider with $M_H=120$ GeV, $g_{HHH}$ can be constrained to about 23% from $HHZ$, while at 3 TeV and 5 ab$^{-1}$, the $HH\nu\bar{\nu}$ channel could reach the order of 9–14% precision depending on $M_H$, with the quartic coupling remaining inaccessible. The results underscore the potential of future $e^+e^-$ colliders to provide a direct test of the Higgs potential and EW symmetry breaking, guiding design and physics priorities for high-luminosity linear colliders.

Abstract

The determination of the shape of the Higgs potential is needed to complete the investigation of the Higgs profile and to obtain a direct experimental proof of the mechanism of electro-weak symmetry breaking. This can be achieved, at a linear collider, by determining the Higgs triple self-coupling g_HHH in the processes e+e--> HHZ and HHnunu and, possibly, the quartic coupling. This paper summarises the results of a study of the expected accuracies on the determination of g_HHH at a TeV-class LC and at a multi-TeV LC. The statistical dilution arising from contributions not sensitive to the triple Higgs vertex, can be reduced by means of variables sensitive to the kinematics and the spin properties of the reactions.

Studying the Higgs Potential at the e+e- Linear Collider

TL;DR

This paper addresses the problem of probing the shape of the Higgs potential by measuring the triple Higgs self-coupling at an linear collider. It analyzes two production channels, and , at TeV-class and multi-TeV energies, using a full simulation chain and observables such as the distribution and the angular variable to mitigate dilution from non- diagrams. The study finds that at a 500 GeV collider with GeV, can be constrained to about 23% from , while at 3 TeV and 5 ab, the channel could reach the order of 9–14% precision depending on , with the quartic coupling remaining inaccessible. The results underscore the potential of future colliders to provide a direct test of the Higgs potential and EW symmetry breaking, guiding design and physics priorities for high-luminosity linear colliders.

Abstract

The determination of the shape of the Higgs potential is needed to complete the investigation of the Higgs profile and to obtain a direct experimental proof of the mechanism of electro-weak symmetry breaking. This can be achieved, at a linear collider, by determining the Higgs triple self-coupling g_HHH in the processes e+e--> HHZ and HHnunu and, possibly, the quartic coupling. This paper summarises the results of a study of the expected accuracies on the determination of g_HHH at a TeV-class LC and at a multi-TeV LC. The statistical dilution arising from contributions not sensitive to the triple Higgs vertex, can be reduced by means of variables sensitive to the kinematics and the spin properties of the reactions.

Paper Structure

This paper contains 4 sections, 4 figures, 3 tables.

Table of Contents

  1. Introduction
  2. The $HHZ$ process
  3. The $HH\nu\bar{\nu}$ process
  4. Conclusions

Figures (4)

  • Figure 1: Left: the dependence of the $HHZ$ cross section on the triple Higgs coupling, normalised to its SM value, for $M_H$ = 120 GeV and two $\sqrt{s}$ values. Right: The distribution of the $HH$ invariant mass in $HHZ$ events orginating from diagrams containing the triple Higgs vertex (light grey) and other diagrams (dark grey).
  • Figure 2: The generated $HH$ invariant mass distribution for $HHZ$ events obtained for $g_{HHH}/g_{HHH}^{SM}=$1.25,1.0,0.75 and 0.5 with the points with error bars showing the expectation for 1 ab$^{-1}$ of SM data at $\sqrt{s}$=0.8 TeV.
  • Figure 3: Left: the dependence of the $HH\nu\bar{\nu}$ cross section on the triple Higgs coupling, normalised to its SM value, for $\sqrt{s}$ = 3 TeV and two $M_H$ values. Right: The $\cos \theta~*$ distribution in $HH\nu\bar{\nu}$ events orginating from diagrams containing the triple Higgs vertex (light grey) and other diagrams (dark grey).
  • Figure 4: The reconstructed $|\cos \theta^*|$ distribution for $HH\nu\bar{\nu}$ events obtained for $g_{HHH}/g_{HHH}^{SM}=$1.25,1.0,0.75 and 0.5 with the points with error bars showing the expectation for 5 ab$^{-1}$ of SM data at $\sqrt{s}$=3.0 TeV.