CP-violating Higgs-gauge boson couplings in $H\nu \bar{\nu}$ production at three energy stages of CLIC

TL;DR

This study investigates CP-violating Higgs-gauge boson interactions in $H u ar{ u}$ production at CLIC, providing limits on new physics couplings across different energy stages using detailed simulations and considering systematic uncertainties.

Contribution

It offers the first comprehensive analysis of CP-violating dimension-six operators in Higgs production at all CLIC energy stages with updated detector and background modeling.

Findings

Best 95% CL limits on $ ilde c_{HW}$ and $ ilde c_{HB}$ at 3 TeV are approximately ±7×10^{-3} and ±3×10^{-2}.

Systematic uncertainties can double the limits on these couplings.

Limits improve with higher energy and luminosity, constraining new physics scenarios.

Abstract

A phenomenological study of CP-violating dimension-six operators via the $e^+e^-\to\nu \bar{\nu} H$ process is performed in a model-independent Standard Model effective field theory framework at all energy stages of CLIC using the updated baseline integrated luminosities. All signal and relevant background events are generated in MadGraph and passed through PYTHIA for parton showering and hadronization at parton level. Detector effects are considered via tuned CLIC detector cards in Delphes. Since we reconstruct the Higgs boson from a pair of b-jets, limits on CP-violating dimension-six couplings are obtained at three $b$-tagging working points: tight, medium and loose defined in the CLIC Delphes card for all three energy stages of CLIC. Our best 95 \% C.L. limits at the loose working point (90 \% b-tagging efficiency) on $\tilde c_{HW}$ and $\tilde c_{HB}$ are $[-7.0\times10^{-3};7.0\times10^{-3}]$ and $[-3.0\times10^{-2};3.0\times10^{-2}]$, respectively at the 3 TeV energy stage of CLIC with an integrated luminosity of 5.0 ab$^{-1}$. Considering a 0.3 \% systematic uncertainty from possible experimental sources worsens the limits on these couplings by a factor of two.