A search for excited electrons produced in pp collisions at √s = 13 TeV 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 TeV, the lower bound for Λ is 11 TeV. In the special case of me∗=Λ, the values of me∗<4.8 TeV are excluded. The presented limits on Λ are more stringent than those obtained in previous searches.
|Number of pages||30|
|Journal||European Physical Journal C|
|Publication status||Published - 26 Sept 2019|
Bibliographical note45 pages in total, author list starting on page 29, 6 figures, 10 tables, published by Eur. Phys. J. C. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2017-22/