Determination of the jet energy scale and resolution at ATLAS using ${Z/\gamma}$--jet events in data at $\sqrt{s}=8$ TeV

The jet-energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector using proton-proton collision data at $\sqrt{s}=8$ TeV corresponding to an integrated luminosity of $20.3~{\rm fb}^{-1}$. The jet energy is probed using the conservation of transverse momentum $(p_{\rm T})$ in events with a jet and a $Z/\gamma$-boson for $20< p_{\rm T}^{\rm{jet}} <800$ GeV and pseudorapidities $|\eta|<0.8$. The uncertainty in the jet energy measured with $Z$--jet events is $1$--$2\%$ for $35<p_{\rm T}^{\rm{jet}} <210$ GeV, and increases to $5$--$8\%$ in the $17<p_{\rm T}^{\rm{jet}}<25$ GeV range. The jet energy is measured with an uncertainty of about $1\%$ for $120<p_{\rm T}^{\rm{jet}} <700$ GeV using $\gamma$--jet events. The jet-energy scale for jets in the pseudorapidity range $0.8<|\eta|<4.5$ is validated in data using $Z$--jet events. After applying $\eta$-dependent corrections, the MC simulation reproduces the jet-energy scale in the forward region within $2\%$. The jet-energy resolution for $20<p_{\rm T}^{\rm{jet}}<700$ GeV and $|\eta|<0.8$ is measured in data using the $Z/\gamma$--jet balance method. The jet-energy resolution in the $20<p_{\rm T}^{\rm{jet}}<80$ GeV range is determined using the $Z$--jet events with an uncertainty of about $20\%$. The uncertainty in the jet-energy resolution is found to be approximately $10\%$ for $80<p_{\rm T}^{\rm{jet}}<700$ GeV using the $\gamma$--jet technique.