Search for a Neutral Gauge Boson with Nonuniversal Fermion Couplings in Vector Boson Fusion Processes in Proton-Proton Collisions at sqrt[s]=13  TeV

The first search for a heavy neutral spin-1 gauge boson (Z^{'}) with nonuniversal fermion couplings produced via vector boson fusion processes and decaying to tau leptons or W bosons is presented. The analysis is performed using LHC data at sqrt[s]=13  TeV, collected from 2016 to 2018 with the CMS experiment and corresponding to an integrated luminosity of 138  fb^{-1}. The data are consistent with the standard model predictions. Upper limits are set on the product of the cross section for production of the Z^{'} boson and its branching fraction to ττ or WW. The presence of a Z^{'} boson decaying to τ^{+}τ^{-} (W^{+}W^{-}) is excluded for masses up to 2.45(1.60) TeV, depending on the Z^{'} boson coupling to standard model weak bosons, and assuming a Z^{'}→τ^{+}τ^{-} (W^{+}W^{-}) branching fraction of 50%.