Search for new resonances in $W\gamma$ and $Z\gamma$ Final States in $pp$ Collisions at $\sqrt{s}=8$ TeV with the ATLAS Detector

This letter presents a search for new resonances decaying to final states with a vector boson produced in association with a high transverse momentum photon, $V\gamma$, with $V=W(\to \mathrm{\ell }\nu )$ or $Z(\rightarrow \ell^{+} \ell^{-})$,where$\ell = e$or$\mu$\mathrm{.}Themeasurementsuse20.3fb$^{-1}$ of proton-proton collision data at a center-of-mass energy of $\sqrt{s}=8$ TeV recorded with the ATLAS detector. No deviations from the Standard Model expectations are found, and production cross section limits are set at 95% confidence level. Masses of the hypothetical $a_T$ and ${\omega }_T$ states of a benchmark Low Scale Technicolor model are excluded in the ranges [275,960] GeV and $[200,700]\cup [750,890]$ GeV, respectively. Limits at 95% confidence level on the production cross section of a singlet scalar resonance decaying to $Z\gamma$ final states have also been obtained for masses below 1180 GeV.