Multi-$Z^{\mathrm{\prime }}$ signatures of spontaneously broken local $U(1{)}^{\mathrm{\prime }}$ symmetry

We discuss multi-$Z^{\mathrm{\prime }}$ signatures coming from decays of Higgs bosons in models with a spontaneously broken $U(1{)}^{\mathrm{\prime }}$ symmetry, which can be observed as “lepton jets” or multi-lepton final states depending on the mass range of new bosons. We consider anomaly-free $U(1{)}^{\mathrm{\prime }}$ models without introducing new fermions except for right-handed neutrinos, in which the Higgs sector is composed of an isospin doublet and a singlet fields with zero and non-zero $U(1{)}^{\mathrm{\prime }}$ charges, respectively. The multi-$Z^{\mathrm{\prime }}$ signatures can then be obtained via the decays of the discovered (extra) Higgs boson $h$ ($\phi$), i.e., $h\to Z^{\mathrm{\prime }}{Z}^{\mathrm{\prime }}$, $\phi \to Z^{\mathrm{\prime }}{Z}^{\mathrm{\prime }}$ and/or $h\to \phi \phi \to 4Z^{\mathrm{\prime }}$ as far as kinematically allowed. We give the upper limit on the branching ratios of $h$ into $Z^{\mathrm{\prime }}{Z}^{\mathrm{\prime }}$ and $4Z^{\mathrm{\prime }}$ from the current experimental data in each model. We also show the deviation in the $hhh$ coupling from the standard model prediction at one-loop level, and find that its amount is typically smaller than 1%.