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Higgs Self-Coupling Measurement at a Linear Collider at 550 GeV

Mikael Berggren, Bryan Bliewert, Jenny List, Dimitris Ntounis, Taikan Suehara, Junping Tian, Julie Munch Torndal, Caterina Vernieri

Abstract

The Higgs mechanism is essential for the success of the Standard Model (SM) and can be experimentally verified with the determination of the Higgs self-coupling. As the simplest model of a Higgs potential, the SM provides a clear prediction of the Higgs self-coupling in terms of the Higgs boson mass and the vacuum expectation value. Any deviations would indicate physics beyond the SM and help guide extended Higgs models. At large enough centre-of-mass energies, double-Higgs production provides tree-level sensitivity to the trilinear Higgs self-coupling. At 550 GeV the leading production mode in $e^+e^-$ comes from di-Higgs strahlung with a small contribution from $WW$-fusion. The most up-to-date ILD projections are extrapolated based on a full simulation analysis from 2014 by incorporating expected improvements in flavour tagging and kinematic reconstruction for event selection, and are presented in this contribution together with the ongoing re-analysis using fast SGV (Simulation a Grande Vitesse) simulations of the ILD detector concept on a full SM background including the aforementioned state-of-the-art reconstruction and analysis tools.

Higgs Self-Coupling Measurement at a Linear Collider at 550 GeV

Abstract

The Higgs mechanism is essential for the success of the Standard Model (SM) and can be experimentally verified with the determination of the Higgs self-coupling. As the simplest model of a Higgs potential, the SM provides a clear prediction of the Higgs self-coupling in terms of the Higgs boson mass and the vacuum expectation value. Any deviations would indicate physics beyond the SM and help guide extended Higgs models. At large enough centre-of-mass energies, double-Higgs production provides tree-level sensitivity to the trilinear Higgs self-coupling. At 550 GeV the leading production mode in comes from di-Higgs strahlung with a small contribution from -fusion. The most up-to-date ILD projections are extrapolated based on a full simulation analysis from 2014 by incorporating expected improvements in flavour tagging and kinematic reconstruction for event selection, and are presented in this contribution together with the ongoing re-analysis using fast SGV (Simulation a Grande Vitesse) simulations of the ILD detector concept on a full SM background including the aforementioned state-of-the-art reconstruction and analysis tools.
Paper Structure (6 sections, 1 equation, 3 figures, 3 tables)

This paper contains 6 sections, 1 equation, 3 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Improvements in reconstruction tools
  3. Updating the ZHH analysis
  4. Extrapolations for projections on the SM Higgs self-coupling
  5. Beyond the SM
  6. Conclusion

Figures (3)

  • Figure 1: Cross sections of double Higgs-strahlung and $\HepParticle{W}{}{}\xspace\HepParticle{W}{}{}\xspace$-fusion as a function of the centre-of-mass energy for two polarisation modes Durig:2016jrs.
  • Figure 2: Invariant mass of the "least Higgs-boson-like" di-jet mass before (a) and after (b) a 4C-fit for the muon channel with $\HepParticle{Z}{}{}\xspace\HepParticle{H}{}{}\xspace\HepParticle{H}{}{}\xspace\to\HepParticle{\HepParticle{\upmu}{}{}\xspace}{}{+}\xspace\HepParticle{\HepParticle{\upmu}{}{}\xspace}{}{-}\xspace\HepParticle{b}{}{}\xspace\HepAntiParticle{\HepParticle{b}{}{}\xspace}{}{}\xspace\HepParticle{b}{}{}\xspace\HepAntiParticle{\HepParticle{b}{}{}\xspace}{}{}\xspace$ compared to $\HepParticle{l}{}{}\xspace\HepParticle{l}{}{}\xspace\HepParticle{q}{}{}\xspace\HepParticle{q}{}{}\xspace\HepParticle{q}{}{}\xspace\HepParticle{q}{}{}\xspace$ background events ZHHnote.
  • Figure 3: Absolute uncertainty on $\kappa_{\uplambda}$ versus itself at LCF550 (a) and beyond LCF550 (b) ZHHnote.