Search for excited electrons and muons with 13 fb$^{-1}$ of proton--proton collisions at $\sqrt{s}=8$ TeV with the ATLAS detector

The ATLAS detector at the LHC is used to search for excited leptons in the electromagnetic radiative decay channel $\ell^*\rightarrow \ell\gamma$. Results are presented based on the analysis of 13.0 fb$^{-1}$ of $pp$ collisions recorded in 2012 at a center-of-mass energy of 8 TeV. No evidence for excited leptons is found, and limits are set on the compositeness scale $\Lambda$ as a function of the excited lepton mass $m_{\ell^*}$. In the special case where $\Lambda = m_{\ell^*}$, excited electron and muon masses below 2.2 TeV are excluded at 95% CL.