A search for Kaluza-Klein excited vector boson resonances, $W_{\mathrm{KK}}$, decaying in cascade to three $W$ bosons via a scalar radion $R$, $W_{\mathrm{KK}}\to WR\to WWW$, in a final state containing two or three massive jets is presented. The search is performed with $\sqrt{s}=13\mathrm{TeV}$ proton-proton collision data collected by the CMS experiment at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of $138{\mathrm{fb}}^{-1}$. Two final states are simultaneously probed, one where the two $W$ bosons produced by the $R$ decay are reconstructed as separate, large-radius, massive jets, and one where they are merged into a single large-radius jet. The observed data are in agreement with the standard model expectations. Limits are set on the product of the $W_{\mathrm{KK}}$ resonance cross section and branching fraction to three $W$ bosons in an extended warped extra-dimensional model and are the first of their kind at the LHC.

• Received 24 December 2021
• Accepted 15 June 2022

DOI:https://doi.org/10.1103/PhysRevD.106.012002

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