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arXiv · 1810.10056

Search for rare decays of Z and Higgs bosons to J$/ψ$ and a photon in proton-proton collisions at $\sqrt{s} =$ 13 TeV

CMS Collaboration
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Abstract

A search is presented for decays of Z and Higgs bosons to a J$/ψ$ meson and a photon, with the subsequent decay of the J$/ψ$ to $μ^+μ^-$. The analysis uses data from proton-proton collisions with an integrated luminosity of 35.9 fb$^{-1}$ at $\sqrt{s} =$ 13 TeV collected with the CMS detector at the LHC. The observed limit on the Z $\to$ J$/ψγ$ decay branching fraction, assuming that the J$/ψ$ meson is produced unpolarized, is 1.4 $\times$ 10$^{-6}$ at 95% confidence level, which corresponds to a rate higher than expected in the standard model by a factor of 15. For extreme-polarization scenarios, the observed limit changes from -13.6 to +8.6% with respect to the unpolarized scenario. The observed upper limit on the branching fraction for H $\to$ J$/ψγ$ where the J$/ψ$ meson is assumed to be transversely polarized is 7.6 $\times$ 10$^{-4}$, a factor of 260 larger than the standard model prediction. The results for the Higgs boson are combined with previous data from proton-proton collisions at $\sqrt{s} =$ 8 TeV to produce an observed upper limit on the branching fraction for H $\to$ J$/ψγ$ that is a factor of 220 larger than the standard model value.

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CMS Collaboration. 2019-02-01. Search for rare decays of Z and Higgs bosons to J$/ψ$ and a photon in proton-proton collisions at $\sqrt{s} =$ 13 TeV. https://doi.org/10.1140/epjc%2Fs10052-019-6562-5

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