A search is presented for a Higgs boson that is produced in association with a Z boson and that decays to an undetected particle together with an isolated photon. The search is performed by the CMS Collaboration at the Large Hadron Collider using a data set corresponding to an integrated luminosity of 137 fb$^{-1}$ recorded at a center-of-mass energy of 13 TeV. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for associated Higgs and Z boson production and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a mass of 125 GeV, assuming the standard model production cross section, this corresponds to an observed (expected) upper limit on this branching fraction of 4.6 (3.6)% at 95% confidence level. These are the first limits on Higgs boson decays to final states that include an undetected massless dark photon.
Observed yields, background estimates after the fit to data, and signal predictions after the event selection in the signal region. The signal size corresponds to $0.1 \sigma_{\mathrm{\mathrm{ZH}}}$ for all three $m_{\mathrm{\mathrm{H}}}$ values shown. The combined statistical and systematic uncertainties are reported.
Observed yields, background estimates after the fit to data, and signal predictions after the event selection in the signal region. The signal size corresponds to $0.1 \sigma_{\mathrm{\mathrm{ZH}}}$ for all three $m_{\mathrm{\mathrm{H}}}$ values shown. The combined statistical and systematic uncertainties are reported.
Expected yields for different processes after several selection stages. The preselection requires two leptons and at least one photon with $\mathrm{p_\mathrm{T}}$ larger than 25, 20, and 25 GeV, respectively; in addition the dilepton $\mathrm{p_\mathrm{T}}$ must be larger than 60 GeV, and the $\mathrm{p_\mathrm{T}}^{\mathrm{miss}}$ larger than 70 GeV. The signal prediction corresponds to $0.1 \sigma_{\mathrm{\mathrm{ZH}}}$ at $m_{H}$ = 125 GeV.
A search for anomalous electroweak production of WW, WZ, and ZZ boson pairs in association with two jets in proton-proton collisions at $\sqrt{s} =$ 13 TeV at the LHC is reported. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$ collected with the CMS detector. Events are selected by requiring two jets with large rapidity separation and invariant mass, one or two leptons (electrons or muons), and a W or Z boson decaying hadronically. No excess of events with respect to the standard model background predictions is observed and constraints on the structure of quartic vector boson interactions in the framework of dimension-8 effective field theory operators are reported. Stringent limits on parameters of the effective field theory operators are obtained. The observed 95% confidence level limits for the S0, M0, and T0 operators are $-$2.7 $<$ f$_{\mathrm{S0}}/ \Lambda^{4}$ $<$ 2.7, $-$1.0 $<$ f$_{\mathrm{M0}}/ \Lambda^{4}$ $<$ 1.0, and $-$0.17 $<$ f$_{\mathrm{T0}}/ \Lambda^{4}$ $<$ 0.16, in units of TeV$^{-4}$. Constraints are also reported on the product of the cross section and branching fraction for vector boson fusion production of charged Higgs bosons as a function of mass from 600 to 2000 GeV. The results are interpreted in the context of the Georgi-Machacek model.
Expected yields from various background processes in $\mathrm{WV}$ and $\mathrm{ZV}$ final states. The combination of the statistical and systematic uncertainties are shown. The predicted yields are shown with their best-fit normalizations from the background-only fit. The aQGC signal yields are shown for two aQGC scenarios with $f_{T2}/ \Lambda^{4} = -0.5$ TeV$^{-4}$ and $f_{T2}/ \Lambda^{4} = -2.5$ TeV$^{-4}$ for the $\mathrm{WV}$ and $\mathrm{ZV}$ channels, respectively. The charged Higgs boson signal yields are also shown for values of $s_{\mathrm{H}}=0.5$ and $m_{\mathrm{H}_{5}}=500$ GeV in the GM model. The statistical uncertainties are shown for the expected signal yields.
Observed and expected lower and upper 95\% CL limits on the parameters of the quartic operators S0, S1, M0, M1, M6, M7, T0, T1, and T2 in $\mathrm{WV}$ and $\mathrm{ZV}$ channels. The last two columns show the observed and expected limits for the combination of the $\mathrm{WV}$ and $\mathrm{ZV}$ channels.
Expected and observed exclusion limits at the 95\% CL as a function of $m(\mathrm{H}^{\pm})$ for $\sigma_\mathrm{VBF}(\mathrm{H}^{\pm}) \, \mathcal{B}(\mathrm{H}^{\pm} \rightarrow \mathrm{W}^{\pm}\mathrm{Z})$ in the $\mathrm{WV}$ final state.
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