A search for new charged heavy gauge W' bosons with the ATLAS detector at the LHC.

This document presents a search for a $W'$ boson, decaying to a top quark and a $b$ quark in an effective coupling approach, using a multivariate method based on boosted decision trees. It reports preliminary exculsion limits on the $W'\rightarrow tb$ cross-section times branching ratio as a function of the $W'$-boson mass and effective couplings. The search covers $W'$-boson masses between 0.5 and 3.0 TeV, for right-handed or left-handed $W'$-boson chiralities, with 14.3 fb$^{-1}$ of proton-proton collisions data produced by the LHC in 2012, at a center-of-mass energy of 8 TeV and collected by the ATLAS detector.