Rare H and Z decays to quarkonia with CMS

Searches for SM Higgs and Z bosons decaying to a $\mathrm{J/\psi}$ and a photon, with subsequent decay of the $\mathrm{J/\psi}$ to $\mu^{+}\mu^{-}$ and the $\mathrm{Z}$ boson rare decay to a $\psi$ meson and two oppositely charged same-flavour leptons, $\ell^+ \ell^-$, where $\psi$ represents contributions from direct $\mathrm{J}/\psi$ and $\psi(\mathrm{2S})\to\mathrm{J}/\psi\, X$, and $\ell=\mu,\mathrm{e}$ are presented. The analyses are performed using data recorded by the CMS detector from proton-proton collisions at center-of-mass energy of $13\,\mathrm{TeV}$ corresponding to an integrated luminosity of $35.9$ $fb^{-1}$. The observed (expected) upper limit on the branching fraction for $\mathrm{H} \rightarrow J/\psi \gamma$ with $m_{\mathrm{H }}=125 ~ \mathrm{GeV}$ is $7.6 (5.2)\times10^{-4}$, $260~(170)$ times larger than the standard model prediction, at $95 \% $ confidence level. The observed (expected) upper limit on the $\mathrm{Z} \rightarrow J/\psi \gamma$ branching fraction is $ 1.4(1.6)\times10^{-6}$, $15~(18)$ times larger than the standard model prediction, at $95 \% $ confidence level. The signal of the $\mathrm{Z}$ boson rare decay to a $\psi$ meson and two oppositely charged same-flavour leptons, $\ell^+ \ell^-$, is observed with a significance in excess of 5 standard deviations. After removing the contributions from $\psi(\mathrm{2S})$ decays to $\mathrm{J}/\psi$, the ratio of the branching fraction of the $\mathrm{Z}\to\mathrm{J}/\psi\,\ell^+\ell^-$, to the decay $\mathrm{Z}\to\mu^+\mu^-\mu^+\mu^-$ within a fiducial phase space is measured to be