PT Journal AU ATLAS Collaboration (Aad, Gea Amos, KR Aparisi Pozo, JA Bailey, AJ Cabrera Urban, S Cardillo, F Castillo Gimenez, V Costa, MJ Didenko Escobar, C Estrada Pastor, O Fiorini, L Fullana Torregrosa, E Fuster, J Garcia, C Garcia Navarro, JE Gonzalez de la Hoz, S Gonzalvo Rodriguez, GR Guerrero Rojas, JGR Higon-Rodriguez, E Lacasta, C Lozano Bahilo, JJ Mamuzic, J Marti-Garcia, S Martinez Agullo, P Miralles Lopez, M Mitsou, VA Monsonis Romero, L Moreno Llacer, M Navarro-Gonzalez, J Poveda, J Prades IbaƱez, A Ruiz-Martinez, A Sabatini, P Salt, J Sanchez Sebastian, V Sayago Galvan, I Soldevila, U Sanchez, J Torro Pastor, E Valero, A Valls Ferrer, JA Villaplana Perez, M Vos, M TI A search for an unexpected asymmetry in the production of e(+)mu(-) and e(-)mu(+) pairs in proton-proton collisions recorded by the ATLAS detector at root s=13 TeV SO Physics Letters B JI Phys. Lett. B PY 2022 BP 137106 EP 22pp VL 830 DI 10.1016/j.physletb.2022.137106 LA English AB This search, a type not previously performed at ATLAS, uses a comparison of the production cross sections for e(+)mu(-) and e(-)mu(+) pairs to constrain physics processes beyond the Standard Model. It uses 139 fb(-1) of proton-proton collision data recorded at root s = 13 TeV at the LHC. Targeting sources of new physics which prefer final states containing e(+)mu(-) and e(-)mu(+), the search contains two broad signal regions which are used to provide model-independent constraints on the ratio of cross sections at the 2% level. The search also has two special selections targeting supersymmetric models and leptoquark signatures. Observations using one of these selections are able to exclude, at 95% confidence level, singly produced smuons with masses up to 640 GeV in a model in which the only other light sparticle is a neutralino when the R-parity-violating coupling lambda(23)(1)' is close to unity. Observations using the other selection exclude scalar leptoquarks with masses below 1880 GeV when g(1R)(eu) = g(1R)(mu c) = 1, at 95% confidence level. The limit on the coupling reduces to g(1R)(eu) = g(1R)(mu c) = 0.46 for a mass of 1420 GeV. ER