A search for excited electrons produced in pp collisions at s = 13 Te via a contact interaction qq¯ → ee∗ is presented. The search uses 36.1 fb- 1 of data collected in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider. Decays of the excited electron into an electron and a pair of quarks (eqq¯) are targeted in final states with two electrons and two hadronic jets, and decays via a gauge interaction into a neutrino and a W boson (νW) are probed in final states with an electron, missing transverse momentum, and a large-radius jet consistent with a hadronically decaying W boson. No significant excess is observed over the expected backgrounds. Upper limits are calculated for the pp→ ee∗→ eeqq¯ and pp→ ee∗→ eνW production cross sections as a function of the excited electron mass me∗ at 95% confidence level. The limits are translated into lower bounds on the compositeness scale parameter Λ of the model as a function of me∗. For me∗<0.5 Te, the lower bound for Λ is 11 Te. In the special case of me∗=Λ, the values of me∗<4.8 Te are excluded. The presented limits on Λ are more stringent than those obtained in previous searches.

Aaboud, M., Aad, G., Abbott, B., Abbott, D.C., Abdinov, O., Abeloos, B., et al. (2019). Search for excited electrons singly produced in proton–proton collisions at √s=13Te with the ATLAS experiment at the LHC. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 79(9) [10.1140/epjc/s10052-019-7295-1].

Search for excited electrons singly produced in proton–proton collisions at √s=13Te with the ATLAS experiment at the LHC

Ceradini F.;Di Micco B.;Di Nardo R.;Orestano D.;Petrucci F.;Rossi E.;