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 s = 13 TeV collected with the CMS detector at the LHC. The observed limit on the Z → J / ψ γ decay branching fraction, assuming that the J / ψ meson is produced unpolarized, is 1.4 × 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 → J / ψ γ where the J / ψ meson is assumed to be transversely polarized is 7.6 × 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 s = 8 TeV to produce an observed upper limit on the branching fraction for H → J / ψ γ that is a factor of 220 larger than the standard model value.
A search is presented for the single production of vector-like quarks in proton-proton collisions at
s
= 13
TeV
. The data, corresponding to an integrated luminosity of 35.9
fb
- 1
, were recorded with the CMS experiment at the LHC. The analysis focuses on the vector-like quark decay into a top quark and a W boson, with one muon or electron in the final state. The mass of the vector-like quark candidate is reconstructed from hadronic jets, the lepton, and the missing transverse momentum. Methods for the identification of b quarks and of highly Lorentz boosted hadronically decaying top quarks and W bosons are exploited in this search. No significant deviation from the standard model background expectation is observed. Exclusion limits at 95% confidence level are set on the product of the production cross section and branching fraction as a function of the vector-like quark mass, which range from 0.3 to 0.03
pb
for vector-like quark masses of 700 to 2000
GeV
. Mass exclusion limits up to 1660
GeV
are obtained, depending on the vector-like quark type, coupling, and decay width. These represent the most stringent exclusion limits for the single production of vector-like quarks in this channel.