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.

Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N.J., et al. (2026). Observation of tt¯γγ production at sqrt(s) =13 TeV withthe ATLAS detector. PHYSICS LETTERS. SECTION B, 874 [10.1016/j.physletb.2026.140195].

Observation of tt¯γγ production at sqrt(s) =13 TeV withthe ATLAS detector

Di Micco, B.;Di Nardo, R.;Montereali, F.;Orestano, D.;Orlandini, R.;
2026-01-01

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
Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N.J., et al. (2026). Observation of tt¯γγ production at sqrt(s) =13 TeV withthe ATLAS detector. PHYSICS LETTERS. SECTION B, 874 [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/11590/560456
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