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FIELDS, PARTICLES, AND NUCLEI
Measurement of $\mathcal{B}r(H \to Z\gamma)$ at the $250$ GeV ILC
E. S. Antonov,
A. G. Drutskoy Lebedev Physical Institute of the Russian Academy of Sciences, Moscow, 119991 Russia
Abstract:
The
$e^+e^- \to HZ$ process with the subsequent decay of the Higgs boson
$H \to Z\gamma $ is studied, where both
$Z$-bosons are reconstructed in the final states with two jets. The analysis is performed using Monte Carlo data samples obtained with detailed ILD detector simulation assuming an integrated luminosity of
$2ab^{-1}$, beam polarizations of
${\mathcal{P}}_{e^-e^+} = (-0.8, +0.3)$, and center-of-mass energy of
$\sqrt{s} = 250$ GeV for the electron–positron International Linear Collider being currently designed. The analysis is repeated for the case of two
$0.9 ab^{-1}$ data samples with polarizations
${\mathcal{P}}_{e^-e^+} = (\mp0.8, \pm0.3)$.
Contributions of the potential background processes are studied using all available ILD MC event samples. The largest background comes from the
$e^+e^- \to W^+W^-$ process supplemented by an energetic photon produced by initial state radiation. To suppress this background, we require that at least one of the
$Z$ bosons decays to
$b$-jets. To reduce the jet reconstruction uncertainties the $M_{\Delta} = M(jj\gamma) - M(jj) + M(Z_{\rm nom})$ variable is used, where
$M(Z_{\rm nom}) = 91.2$ GeV. The
$M_{\Delta}$ distributions are obtained for the studied signal and backgrounds to estimate the expected accuracy of the
${\mathcal B}r(H \to Z\gamma)$ measurement. The accuracy is
$22\%$ for the option of the single polarization sample described above and deteriorate to
$24\%$ in case of the sample with two polarizations. The proposed method can be applied at any future
$e^+e^-$ collider.
Received: 20.12.2022
Revised: 24.12.2022
Accepted: 25.12.2022
DOI:
10.31857/S1234567823030011