ATLAS collaboration (2858 authors)Aguilar-Saavedra, Juan AntonioAmor Dos Santos, Susana PatriciaAnjos, NunoAraque, Juan PedroCantrill, RobertCarvalho, JoãoCastro, Nuno FilipeConde Muiño, PatriciaDa Cunha Sargedas De Sousa, Mario JoseFiolhais, MiguelGalhardo, BrunoGomes, AgostinhoGonçalo, RicardoJorge, PedroLopes, LourencoMachado Miguens, JoanaMaio, AméliaManeira, JoséOnofre, AntónioPalma, AlbertoPedro, RutePina, João AntonioSantos, HelenaSaraiva, JoãoSilva, JoséTavares Delgado, AdemarVeloso, FilipeWolters, Helmut2019-02-042019-02-042016-04-28http://dx.doi.org/10.1140/epjc/s10052-016-4065-1http://hdl.handle.net/10400.26/26931The distribution of particles inside hadronic jets produced in the decay of boosted W and Z bosons can be used to discriminate such jets from the continuum background. Given that a jet has been identified as likely resulting from the hadronic decay of a boosted W or Z boson, this paper presents a technique for further differentiating Z bosons from W bosons. The variables used are jet mass, jet charge, and a b-tagging discriminant. A likelihood tagger is constructed from these variables and tested in the simulation of $W'\rightarrow WZ$ for bosons in the transverse momentum range 200 GeV  $<p_\text {T}<$  400 GeV in $\sqrt{s}=8$ TeV pp collisions with the ATLAS detector at the LHC. For Z-boson tagging efficiencies of $\epsilon _Z=90$ , 50, and $10\,\%$ , one can achieve $W^+$ -boson tagging rejection factors ( $1/\epsilon _{W^+}$ ) of 1.7, 8.3 and 1000, respectively. It is not possible to measure these efficiencies in the data due to the lack of a pure sample of high $p_\text {T}$ , hadronically decaying Z bosons. However, the modelling of the tagger inputs for boosted W bosons is studied in data using a $t\bar{t}$ -enriched sample of events in 20.3 fb ${}^{-1}$ of data at $\sqrt{s}=8$ TeV. The inputs are well modelled within uncertainties, which builds confidence in the expected tagger performance.engjournal article2019-02-04