Search for excited electrons and muons in $\sqrt {s}=8$ TeV proton–proton collisions with the ATLAS detector

G Aad, T Abajyan, B Abbott, J Abdallah, S Abdel Khalek, O Abdinov, R Aben, B Abi, M Abolins, O S AbouZeid, H Abramowicz, H Abreu (+2035 others)
2013 New Journal of Physics  
The ATLAS detector at the LHC is used to search for excited electrons and excited muons in the channel pp -> ll* -> llgamma, assuming that excited leptons are produced via contact interactions. The analysis is based on 13 fb-1 of pp collisions at a centre-of-mass energy of 8 TeV. No evidence for excited leptons is found, and a limit is set at the 95% credibility level on the cross section times branching ratio as a function of the excited-lepton mass m_l*. For m_l* > 0.8 TeV, the respective
more » ... r limits on sigma*B(l* -> lgamma) are 0.75 fb and 0.90 fb for the e* and mu* searches. Limits on sigma*B are converted into lower bounds on the compositeness scale Lambda. In the special case where Lambda = m_l*, excited-electron and excited-muon masses below 2.2 TeV are excluded.
doi:10.1088/1367-2630/15/9/093011 fatcat:hdcr4i4upnhblbfo3zf3uv4gre