Measurement of the mass of Higgs boson through HZ production at FCC-ee

TL;DR

This study demonstrates a precise, model-independent method to measure the Higgs boson mass via ZH production at FCC-ee, utilizing recoil mass analysis to reduce uncertainties and improve coupling measurements.

Contribution

It introduces a recoil mass technique for Higgs mass measurement at FCC-ee, enabling high-precision, decay-mode-independent analysis of the HZZ coupling.

Findings

Achieved precise Higgs mass measurement at 240 and 365 GeV energies.

Reduced systematic uncertainties through recoil mass method.

Showed potential for future lepton colliders to probe Higgs properties with high accuracy.

Abstract

The associated production of a Higgs boson with a $Z$ boson in the collisions of electron and positron beams at Future Circular Collider (FCC-ee) have been studied. Here, the $Z$ boson decays into dileptons, while the Higgs boson decays to all possible channels, mostly to the $b\bar{b}$. The collisions provide a clean and powerful channel to probe the ($HZZ$) coupling at future lepton colliders. Following the event generation, the analysis is performed using the recoil mass method, which allows model-independent reconstruction of the Higgs boson depending on the kinematics of the final-state leptons. This method enables precise identification of the Higgs signal peak independent of its decay mode and significantly reduces systematic uncertainties. The recoil mass distributions from the signal process ($e^+e^- \to HZ$, $Z \to l^+l^-$) and the main backgrounds ($ZZ$, $WW$, $t\bar{t}$ and other standard model processes) have been analyzed using a dedicated analysis code. Monte Carlo simulations corresponding to an integrated luminosity of $5$ ab$^{-1}$ have been used for the analysis, assuming the high performance of the IDEA detector concept. The results are presented for center-of-mass energies of $\sqrt{s} = 240$ GeV and $\sqrt{s} = 365$ GeV to compare the sensitivities and highlight the potential of future $e^+e^-$ colliders in probing the $HZZ$ interaction with high precision.