Measurement of $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}HZ)\ifmmode\times\else\texttimes\fi{}\mathcal{B}r(H\ensuremath{\rightarrow}Z{Z}^{*})$ at the 250 GeV ILC

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Measurement of $σ (e^{+} e^{-} \to H Z) \times B r (H \to Z Z^{*})$ at the 250 GeV ILC

E. Antonov and A. Drutskoy

Phys. Rev. D 104, 093007 – Published 18 November 2021

Abstract

We report on studies of the $e^{+} e^{-} \to H Z$ process with the subsequent decay of the Higgs boson $H \to Z Z^{⋆}$ , where the $Z Z^{⋆}$ combination is reconstructed in the final states with two jets and two leptons. The analysis is performed using Monte Carlo data samples obtained with detailed ILD detector simulation assuming the integrated luminosity $2 {ab}^{- 1}$ , the beam polarizations $P_{e^{-} e^{+}} = (- 0.8, + 0.3)$ , and the center-of-mass energy $\sqrt{s} = 250 GeV$ . The analysis is also repeated for the case of two $0.9 {ab}^{- 1}$ data samples with polarizations $P_{e^{-} e^{+}} = (\mp 0.8, \pm 0.3)$ . The process is measured in four decay channels, which correspond to two combinations for the Higgs final states and two decay modes of the directly produced $Z$ boson, $Z \to q \bar{q}$ and $Z \to ν \bar{ν}$ . To obtain the Higgs boson mass distributions, we used the variables $M (j j ℓ ℓ)$ and $M_{Δ} = M (j j ℓ ℓ) - M (j j) + M (Z_{nom})$ , where $M (Z_{nom}) = 91.2 GeV$ . Contributions of the potential background processes are taken into account based on the available MC event samples. We propose a model-independent method for obtaining the width of the Higgs boson using the measurement of the $e^{+} e^{-} \to H Z$ process.

Received 23 August 2021
Accepted 15 October 2021

DOI:https://doi.org/10.1103/PhysRevD.104.093007

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Higgs bosons

Particles & Fields

Authors & Affiliations

E. Antonov and A. Drutskoy

P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991, Russia

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Vol. 104, Iss. 9 — 1 November 2021

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Figure 1
The $M_{Δ} = M (j j ℓ ℓ) - M (j j) + M (Z_{nom})$ mass distributions are shown for the $e^{+} e^{-} \to Z_{1} (j_{1} j_{2}) H (Z Z^{⋆})$ process followed by the decays $Z \to j_{3} j_{4}$ and $Z^{⋆} \to ℓ^{+} ℓ^{-}$ . (a) The distributions are presented separately for the signal (full dots) and background (shaded histogram). The fit results are overlaid: a blue solid curve for the signal and a red dashed curve for background. (b) The sum of the signal and background contributions is shown by full dots together with the fit results: red dashed curve for background and the red solid curve for the sum. The functions and the fit methods are described in the text.
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Figure 2
The $M (j_{1} j_{2})$ (hatched histogram) and $M (j_{3} j_{4})$ (shaded histogram) mass distributions are shown for the $e^{+} e^{-} \to Z_{1} (j_{1} j_{2}) H (Z Z^{⋆})$ process followed by the decays $Z \to j_{3} j_{4}$ and $Z^{⋆} \to ℓ^{+} ℓ^{-}$ .
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Figure 3
The distribution of the number of the signal events obtained from the toy MC fits (dots with errors) is shown together with a fit by the Gaussian function (curve) as described in the text.
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Figure 4
The $M (j j ℓ ℓ)$ mass distributions are shown for the $e^{+} e^{-} \to Z_{1} (j_{1} j_{2}) H (Z Z^{⋆})$ process followed by the decays $Z \to ℓ^{+} ℓ^{-}$ and $Z^{⋆} \to j_{3} j_{4}$ . The distributions are presented separately for the signal (full dots) and background (shaded histogram).
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Figure 5
The $M_{Δ} = M (j j ℓ ℓ) - M (j j) + M (Z_{nom})$ mass distributions are shown for the $e^{+} e^{-} \to Z_{1} (ν \bar{ν}) H (Z Z^{⋆})$ process followed by the decays $Z \to j j$ and $Z^{⋆} \to ℓ^{+} ℓ^{-}$ . (a) The distributions are presented separately for the signal (full dots) and background (shaded histogram). The fit results are overlaid: a blue solid curve for the signal and a red dashed curve for background. (b) The sum of the signal and background contributions is shown by full dots together with the fit results: red dashed curve for background and the red solid curve for the sum. The functions and the fit methods are described in the text.
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Figure 6
The $M (j j ℓ ℓ)$ mass distribution is shown for the $e^{+} e^{-} \to Z_{1} (ν \bar{ν}) H (Z Z^{⋆})$ process followed by the decays $Z \to ℓ^{+} ℓ^{-}$ and $Z^{⋆} \to j j$ . (a) The distributions are presented separately for the signal (full dots) and background (shaded histogram). The fit results are overlaid: a blue solid curve for the signal and a red dashed curve for background. (b) The sum of the signal and background contributions is shown by full dots together with the fit results: red dashed curve for background and the red solid curve for the sum. The functions and the fit methods are described in the text.
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Physical Review D

covering particles, fields, gravitation, and cosmology

Measurement of $σ (e^{+} e^{-} \to H Z) \times B r (H \to Z Z^{*})$ at the 250 GeV ILC

E. Antonov and A. Drutskoy

Phys. Rev. D 104, 093007 – Published 18 November 2021

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Physical Review D

covering particles, fields, gravitation, and cosmology

Measurement of σ(e+e−→HZ)×Br(H→ZZ*) at the 250 GeV ILC

E. Antonov and A. Drutskoy

Phys. Rev. D 104, 093007 – Published 18 November 2021

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Measurement of $σ (e^{+} e^{-} \to H Z) \times B r (H \to Z Z^{*})$ at the 250 GeV ILC