A measurement of the charge asymmetry in top-quark pair (tt¯) production in association with a photon is presented. The measurement is performed in the single-lepton tt¯ decay channel using proton–proton collision data collected with the ATLAS detector at the Large Hadron Collider at CERN at a centre-of-massenergy of 13 TeV during the years 2015–2018, corresponding to an integrated luminosity of 139 fb−1. The charge asymmetry is obtained from the distribution of the difference of the absolute rapidities of the top quark and antiquark using a profile likelihood unfolding approach. It is measured to be AC = −0.003 ± 0.029 in agreement with the Standard Model expectation.

Aad, G., Abbott, B., Abbott, D., Abeling, K., Abidi, S., Aboulhorma, A., et al. (2023). Measurement of the charge asymmetry in top-quark pair production in association with a photon with the ATLAS experiment. PHYSICS LETTERS. SECTION B, 843, 137848-1-137848-21 [10.1016/j.physletb.2023.137848].

Measurement of the charge asymmetry in top-quark pair production in association with a photon with the ATLAS experiment

Alberghi, G. L.;Alfonsi, F.;Bindi, M.;Boscherini, D.;Cabras, G.;Carratta, G.;Cavalli, N.;De Castro, S.;Fabbri, F.;Fabbri, L.;Franchini, M.;Gabrielli, A.;Lasagni Manghi, F.;Massa, L.;