This paper presents the first observation of top-quark pair production in association with two photons (tt¯γγ). The measurement is performed in the single-lepton decay channel using proton-proton collision data collected by the ATLAS detector at the Large Hadron Collider. The data correspond to an integrated luminosity of 140 fb−1 recorded during Run 2 at a centre-of-mass energy of 13 TeV. The tt¯γγ production cross section, measured in a fiducial phase space based on particle-level kinematic criteria for the lepton, photons, and jets, is found to be 2.42−0.53+0.58fb, corresponding to an observed significance of 5.2 standard deviations. Additionally, the ratio of the production cross section of tt¯γγ to top-quark pair production in association with one photon is determined, yielding (3.30−0.65+0.70)×10−3.

Observation of t(t)over-barγγ production at √s=13 TeV with the ATLAS detector / Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N.J., Abidi, S.H., Aboelela, M., Aboulhorma, A., Abramowicz, H., Abulaiti, Y., Acharya, B.S., Ackermann, A., Bourdarios, C.A., Adamczyk, L., Addepalli, S.V., Addison, M.J., Adelman, J., Adiguzel, A., Adye, T., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 874:(2026). [10.1016/j.physletb.2026.140195]

Observation of t(t)over-barγγ production at √s=13 TeV with the ATLAS detector

Aloisio, A.;Alviggi, M.;Canale, V.;Casolaro, P.;Cirotto, F.;D'Avanzo, A.;Della Pietra, M.;Massarotti, P.;Rossi, E.;
2026

Abstract

This paper presents the first observation of top-quark pair production in association with two photons (tt¯γγ). The measurement is performed in the single-lepton decay channel using proton-proton collision data collected by the ATLAS detector at the Large Hadron Collider. The data correspond to an integrated luminosity of 140 fb−1 recorded during Run 2 at a centre-of-mass energy of 13 TeV. The tt¯γγ production cross section, measured in a fiducial phase space based on particle-level kinematic criteria for the lepton, photons, and jets, is found to be 2.42−0.53+0.58fb, corresponding to an observed significance of 5.2 standard deviations. Additionally, the ratio of the production cross section of tt¯γγ to top-quark pair production in association with one photon is determined, yielding (3.30−0.65+0.70)×10−3.
2026
Observation of t(t)over-barγγ production at √s=13 TeV with the ATLAS detector / Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N.J., Abidi, S.H., Aboelela, M., Aboulhorma, A., Abramowicz, H., Abulaiti, Y., Acharya, B.S., Ackermann, A., Bourdarios, C.A., Adamczyk, L., Addepalli, S.V., Addison, M.J., Adelman, J., Adiguzel, A., Adye, T., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 874:(2026). [10.1016/j.physletb.2026.140195]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/1047234
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