arXiv subjects

Bryan Bliewert

Publications and source records attributed to Bryan Bliewert.

4 recordsLinked to original sources

arXiv2026

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

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.

hep-ex↗

arXiv2025

Update of the Higgs Self-coupling Projections from Di-Higgs Production in Detailed Simulation of the ILD Concept

This contribution summarizes the update of the projections for the determination of the tri-linear Higgs self-coupling from di-Higgs production at future $e^+e^-$ colliders. In particular, we will present an update of the analysis of $ZHH$ production at 500 GeV in detailed simulations of the ILD concept, covering the $HH\rightarrow b\bar{b}b\bar{b}$ and $Z\rightarrow q\bar{q} / e^+e^- / \mu^+\mu^- /\nu\bar{\nu}$ channels. Based on the experience of previous analyses, we will extrapolate these to contain some of the remaining decay modes, e.g. $HH\rightarrow b\bar{b} WW^*$ or $Z\rightarrow \tau^+\tau^-$, as well as the contribution from the $WW$ fusion production mode. We will study the dependency of the results on the centre-of-mass energy (in particular discussing 550 GeV and 1 TeV) as well as on the value of the trilinear coupling realised in nature.

hep-ex↗

arXiv2024

Higgs Self-coupling Strategy at Linear e$^+$e$^-$ Colliders

The determination of the Higgs self-coupling is a key target for future colliders, in particular through di-Higgs production at $e^+e^-$ Linear Colliders with $\sqrt{s} > 450$\,GeV, e.g.\ ILC, C3 or CLIC. This contribution will discuss the roles and the interplay of di-Higgs production processes at various collider energies, including the case of non-SM values of the self-coupling. Previous studies, already based on Geant4-based detector simulation, established that the Higgs self-coupling can be extracted with $10-27\%$ precision and provided a solid understanding of the limiting factors. This provides a robust starting point to explore the potential of more modern and sophisticated reconstruction and analysis techniques. We summarize the impact of advanced, often machine-learning-based algorithms, including e.g.\ jet clustering, kinematic fitting and matrix element-inferred likelihoods on the reconstruction of $ZHH$ events and before discussing the dependence of the projected precision on the center-of-mass energy and on the actual value of the self-coupling.

hep-ex↗

arXiv2024

Towards an update of the ILD ZHH analysis

The double Higgs-strahlungs process $e^+e^- \rightarrow ZHH$ allows to access the Higgs self-coupling at center-of-mass energies above $450$ GeV. Its cross-section exhibits a very different behavior as a function of the value of the self-coupling than fusion-type processes like gluon-gluon fusion at LHC (and future hadron colliders) and $WW$ / $ZZ$ fusion at higher energy lepton colliders. Therefore it adds unique information to the picture, in particular should the value of the Higgs self-coupling differ from its Standard Model prediction. The last full evaluation of the potential of the ILC to measure this process is more than ten years old, and since then many of the reconstruction tools have received very significant improvements. This contribution presents the ongoing work in the ILD collaboration to update the ZHH projections for the next European Particle Physics Strategy Update.

hep-ex↗