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Di-Higgs phenomenology: The forgotten channel

Christoph Englert, Frank Krauss, Michael Spannowsky, Jennifer Thompson

TL;DR

This paper investigates tt̄hh production at the LHC as a complementary probe of the Higgs self-coupling η. By analyzing semi-leptonic tt decays with h→bb in a high-multiplicity, high-jet-multiplicity final state and reconstructing Higgs and top candidates via a χ^2 method, the authors quantify signal-to-background prospects at 14 TeV and project implications for Run 2 data. They show that the tt̄hh channel, which benefits from constructive interference with λ, can yield a 95% CLs bound of λ ≲ 2.51 λ_SM with 3 ab⁻¹, providing an important piece of a global di-Higgs program alongside GF and WBF channels. The work highlights the added value of including tt̄hh in global fits to constrain the Higgs self-coupling and to potentially reveal deviations indicating new physics in electroweak symmetry breaking.

Abstract

Searches for multi-Higgs final states allow to constrain parameters of the SM (or extensions thereof) that directly relate to the mechanism of electroweak symmetry breaking. Multi-Higgs production cross sections, however, are small and the phenomenologically accessible final states are challenging to isolate in the busy multi-jet hadron collider environment of the LHC run 2. This makes the necessity to extend the list of potentially observable production mechanisms obvious. Most of the phenomenological analyses in the past have focused on $gg\to hh+jets$; in this paper we study $pp\to t\bar t hh$ at LHC run 2 and find that this channel for $h\to b\bar b$ and semi-leptonic and hadronic top decays has the potential to provide an additional handle to constrain the Higgs trilinear coupling in a global fit at the end of run 2.

Di-Higgs phenomenology: The forgotten channel

TL;DR

This paper investigates tt̄hh production at the LHC as a complementary probe of the Higgs self-coupling η. By analyzing semi-leptonic tt decays with h→bb in a high-multiplicity, high-jet-multiplicity final state and reconstructing Higgs and top candidates via a χ^2 method, the authors quantify signal-to-background prospects at 14 TeV and project implications for Run 2 data. They show that the tt̄hh channel, which benefits from constructive interference with λ, can yield a 95% CLs bound of λ ≲ 2.51 λ_SM with 3 ab⁻¹, providing an important piece of a global di-Higgs program alongside GF and WBF channels. The work highlights the added value of including tt̄hh in global fits to constrain the Higgs self-coupling and to potentially reveal deviations indicating new physics in electroweak symmetry breaking.

Abstract

Searches for multi-Higgs final states allow to constrain parameters of the SM (or extensions thereof) that directly relate to the mechanism of electroweak symmetry breaking. Multi-Higgs production cross sections, however, are small and the phenomenologically accessible final states are challenging to isolate in the busy multi-jet hadron collider environment of the LHC run 2. This makes the necessity to extend the list of potentially observable production mechanisms obvious. Most of the phenomenological analyses in the past have focused on ; in this paper we study at LHC run 2 and find that this channel for and semi-leptonic and hadronic top decays has the potential to provide an additional handle to constrain the Higgs trilinear coupling in a global fit at the end of run 2.

Paper Structure

This paper contains 6 sections, 10 equations, 3 figures, 1 table.

Table of Contents

  1. Introduction
  2. Signal Cross Section Sensitivity and Event Generation
  3. $t\bar{t} hh$ at LHC run 2
  4. Final State Reconstruction
  5. Discussion
  6. Summary and Conclusions

Figures (3)

  • Figure 1: Differential distributions at 14 TeV centre of mass energy of the inclusive maximum Higgs transverse momentum for different values of the Higgs trilinear coupling $\lambda$. The lower panel displays the ratio of the $\max p_T(h)$ distribution with respect to the SM ($\lambda=\lambda_{\text{SM}}$).
  • Figure 2: Reconstructed invariant mass of bottom-quark pairs based on Eq. \ref{['eq:mbb1mbb2']} for $\lambda = \lambda_{\mathrm{SM}}$.
  • Figure 3: Expected confidence levels for the analysis of Sec. \ref{['sec:rec']} as a function of the trilinear Higgs coupling $\lambda$.