Abstract
A search for the production of top-quark pairs with the same electric charge (π‘π‘ or π‘Β―π‘Β―) is presented. The analysis uses protonβproton collision data at βπ = 13 TeV, recorded by the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 140 fbβ1. Events with two same-charge leptons and at least two π-tagged jets are selected. Neural networks are employed to define two selections sensitive to additional couplings beyond the Standard Model that would enhance the production rate of same-sign top-quark pairs. No significant signal is observed, leading to an upper limit on the total production cross-section of same-sign top-quark pairs of 1.6 fb at 95 % confidence level. Corresponding limits on the three Wilson coefficients associated with the O(1)π‘π’ , O(1)ππ’, and O(8)ππ’ operators in the Standard Model Effective Field Theory framework are derived.