Search for resonances with boson-tagged jets in 15.5 fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 13$ TeV collected with the ATLAS detector

Resonances with masses in the range 1.2<$m_{VV}$<3.5 TeV decaying into WW, WZ, or ZZ boson pairs reconstructed as boosted-boson jets, are searched for in 15.5fb$^{−1}$ of proton-proton collision data at a centre-of-mass energy of $\sqrt{s}=13$ TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. No significant deviations from the background expectations are seen. Exclusion limits at the 95 confidence level are set on the production cross section times branching ratio to WZ and WW final states of a new Heavy Vector Triplet, and to WW and ZZ final states of Kaluza-Klein excitations of the graviton in a bulk Randall-Sundrum model, as a function of resonance mass. The additional charged (neutral) vector boson with couplings predicted by the model A assuming ($g_V$=1) of the Heavy Vector Triplet phenomenological Lagrangian, W′(Z′) is excluded in the mass range 1.2-1.9 (1.2-1.8) TeV at the 95% confidence level through its decay to WZ (WW). For the model B ($g_V$=3) of the Heavy Vector Triplet, W′(Z′) is excluded in the mass range 1.2-3.0 (1.2-1.9) TeV at the 95% confidence level through its decay to WZ (WW).