Clark, Brian LeeFranklin, MelissaHuth, JohnIppolito, ValerioLazovich, TomoLopez Mateos, DavidMercurio, KevinMorii, MasahiroSpearman, WilliamSun, SiyuanTolley, EmmaTuna, AlexanderYen, AndyZambito, Stefano2017-12-052016ATLAS Collaboration. 2016. “A search for prompt lepton-jets in pp collisions at s√= 8 TeV with the ATLAS detector.” Journal of High Energy Physics 2016 (2) (February). doi:10.1007/jhep02(2016)062.1029-8479http://nrs.harvard.edu/urn-3:HUL.InstRepos:34487706A search is presented for a new, light boson with a mass of about 1 GeV and decaying promptly to jets of collimated electrons and/or muons (lepton-jets). The analysis is performed with 20.3 fb−1 of data collected by the ATLAS detector at the Large Hadron Collider in proton--proton collisions at a centre-of-mass energy of 8 TeV. Events are required to contain at least two lepton-jets. This study finds no statistically significant deviation from predictions of the Standard Model and places 95\% confidence-level upper limits on the contribution of new phenomena beyond the SM, incuding SUSY-portal and Higgs-portal models, on the number of events with lepton-jets.en-USJournal Article2017-12-0510.1007/JHEP02(2016)062