  A search is presented for narrow diboson resonances decaying to $WW$ or $WZ$
in the final state where one $W$ boson decays leptonically (to an electron or a
muon plus a neutrino) and the other $W/Z$ boson decays hadronically. The
analysis is performed using an integrated luminosity of 20.3 fb$^{-1}$ of $pp$
collisions at $\sqrt{s}$ = 8 TeV collected by the ATLAS detector at the LHC. No
evidence for resonant diboson production is observed, and resonance masses
below 700 GeV and 1490 GeV are excluded at 95% confidence level for the spin-2
Randall-Sundrum bulk graviton $G^*$ with coupling constant of 1.0 and the
extended gauge model $W'$ boson respectively.
