CMS-PAS-SMP-22-012

CMS-PAS-SMP-22-012
Search for the rare decays of the Z and Higgs bosons to a $\mathrm{J}/\psi$ or $\psi^{\prime}$ meson and a photon in proton-proton collisions at $\sqrt{s}=$ 13 TeV
CMS Collaboration
30 November 2023

Abstract: A search is performed for the rare decays of the Z and Higgs bosons to a photon and a charmed meson $\mathrm{J}/\psi$ or $\psi^{\prime}$ , which subsequentially decays to a pair of muons. The data set corresponds to an integrated luminosity of 123 fb $^{-1}$ of proton-proton collisions at $\sqrt{s}=$ 13 TeV collected with the CMS detector at the LHC. The presence of two resonances in the signal is used to discriminate and estimate the non-resonant backgrounds. No evidence for branching fractions to these rare decay channels larger than predicted in the standard model is observed. Upper limits at 95% confidence level are set on $\mathcal{B}(\mathrm{H}\to\mathrm{J}/\psi\gamma) < 2.6 \times 10^{-4}$ , $\mathcal{B}(\mathrm{H}\to\psi^{\prime}\gamma) < 9.9 \times 10^{-4}$ , $\mathcal{B}(\mathrm{Z}\to\mathrm{J}/\psi\gamma) < 0.6 \times 10^{-6}$ and $\mathcal{B}(\mathrm{Z}\to\psi^{\prime}\gamma) < 1.3 \times 10^{-6}$ . The ratio of the Higgs boson coupling modifiers $\kappa_{c}/\kappa_{\gamma}$ is constrained to be in the interval $(-157,+199)$ at 95% confidence level. When assuming $\kappa_{\gamma}=$ 1, the observed interval becomes $(-166,+208)$ .
Links: CDS record (PDF) ; Physics Briefing ; CADI line (restricted) ; These preliminary results are superseded in this paper, Submitted to PLB. The superseded preliminary plots can be found here.

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