This Letter presents the first evidence of the simultaneous production of two Z bosons and one photon with the ATLAS detector at the Large Hadron Collider. The measurement is performed using the full Run-2 dataset, recorded from 2015 to 2018, of proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 140  fb^{-1}. The fully leptonic final state with four leptons and one photon is analyzed, pp -> Z Z gamma -> l+ l- lprime+ lprime- gamma with l, lprime = e or mu. This final state is measured in a fiducial region where photon final-state radiation is minimized, and the photon has a transverse momentum of p_{T}^{gamma} > 20  GeV. Eight events are selected, with a background estimate of 0.92 +- 0.15. This results in an observed (expected) significance of the Z Z gamma final state of 4.4 sigma (4.0 sigma). The measured cross section for pp -> Z Z gamma -> l+ l- lprime+ lprime- gamma in the fiducial region is sigma_{Z Z gamma} = 0.144_{-0.051}^{+0.065}(stat)_{-0.004}^{+0.008}(syst)  fb, in agreement with the standard model prediction of sigma_{fid}^{SM}=0.130+-0.006  fb.

Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N. ., et al. (2026). Evidence of Z Z gamma Production with the ATLAS Detector. PHYSICAL REVIEW LETTERS, 137(9), 091804 [10.1103/jngg-1nf3].

Evidence of Z Z gamma Production with the ATLAS Detector

Aielli, G.;Camarri, P.;Cerrito, L.;De Sanctis, U.;Di Ciaccio, A.;
2026-08-28

Abstract

This Letter presents the first evidence of the simultaneous production of two Z bosons and one photon with the ATLAS detector at the Large Hadron Collider. The measurement is performed using the full Run-2 dataset, recorded from 2015 to 2018, of proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 140  fb^{-1}. The fully leptonic final state with four leptons and one photon is analyzed, pp -> Z Z gamma -> l+ l- lprime+ lprime- gamma with l, lprime = e or mu. This final state is measured in a fiducial region where photon final-state radiation is minimized, and the photon has a transverse momentum of p_{T}^{gamma} > 20  GeV. Eight events are selected, with a background estimate of 0.92 +- 0.15. This results in an observed (expected) significance of the Z Z gamma final state of 4.4 sigma (4.0 sigma). The measured cross section for pp -> Z Z gamma -> l+ l- lprime+ lprime- gamma in the fiducial region is sigma_{Z Z gamma} = 0.144_{-0.051}^{+0.065}(stat)_{-0.004}^{+0.008}(syst)  fb, in agreement with the standard model prediction of sigma_{fid}^{SM}=0.130+-0.006  fb.
28-ago-2026
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Settore PHYS-01/A - Fisica sperimentale delle interazioni fondamentali e applicazioni
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Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N. ., et al. (2026). Evidence of Z Z gamma Production with the ATLAS Detector. PHYSICAL REVIEW LETTERS, 137(9), 091804 [10.1103/jngg-1nf3].
Aad, G; Aakvaag, E; Abbott, B; Abdelhameed, S; Abeling, K; Abicht, N ; Abidi, S ; Aboelela, M; Aboulhorma, A; Abramowicz, H; Acharya, B ; Ackermann, A...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/474288
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