Search for W - GT tb - GT qqbb decays in pp collisions at root s=8 TeV with the ATLAS detector

Abstract

A search for a massive W gauge boson decaying to a top quark and a bottom quark is performed with the ATLAS detector in pp collisions at the LHC. The datasetwas taken at a centre-of-mass energy of root s = 8 TeV and corresponds to 20.3 fb(-1) of integrated luminosity. This analysis is done in the hadronic decay mode of the top quark, where novel jet substructure techniques are used to identify jets from high-momentum top quarks. This allows for a search for high-mass W bosons in the range 1.5-3.0 TeV. b-tagging is used to identify jets originating from b-quarks. The data are consistent with Standard Model background-only expectations, and upper limits at 95% confidence level are set on the W - GT tb cross section times branching ratio ranging from 0.16 pb to 0.33 pb for left-handed W bosons, and ranging from 0.10 pb to 0.21 pb for W bosons with purely righthanded couplings. Upper limits at 95% confidence level are set on the W-boson coupling to tb as a function of the W mass using an effective field theory approach, which is independent of details of particular models predicting a W boson.