This Letter reports the observation of W+W−γ triboson production in 140 fb−1 of data collected by the ATLAS detector from proton–proton collisions at a centre-of-mass energy of s = 13 TeV at the LHC. Events with an opposite-charge eμ pair, a high transverse-momentum photon, and significant missing transverse momentum are considered. The observed (expected) significance of the signal is 5.9 (6.0) standard deviations. The measured fiducial cross-section, defined for the W+W−γ→e±μ∓νν¯γ final state is 6.2 ± 0.8 (stat.) ± 0.6 (sys.) fb, in good agreement with the Standard Model prediction of 6.1−0.7+1.0 fb. Constraints on the Wilson coefficients of 13 dimension-8 operators describing physics beyond the Standard Model through anomalous quartic gauge-boson couplings are derived using the effective field theory framework.

Observation of $W^{+}W^{-}\gamma$ production in pp collisions at = 13 TeV with the ATLAS detector and constraints on anomalous quartic gauge-boson couplings

M. Capua;A. Mastroberardino;E. Meoni;M. Schioppa;E. Tassi;
2026-01-01

Abstract

This Letter reports the observation of W+W−γ triboson production in 140 fb−1 of data collected by the ATLAS detector from proton–proton collisions at a centre-of-mass energy of s = 13 TeV at the LHC. Events with an opposite-charge eμ pair, a high transverse-momentum photon, and significant missing transverse momentum are considered. The observed (expected) significance of the signal is 5.9 (6.0) standard deviations. The measured fiducial cross-section, defined for the W+W−γ→e±μ∓νν¯γ final state is 6.2 ± 0.8 (stat.) ± 0.6 (sys.) fb, in good agreement with the Standard Model prediction of 6.1−0.7+1.0 fb. Constraints on the Wilson coefficients of 13 dimension-8 operators describing physics beyond the Standard Model through anomalous quartic gauge-boson couplings are derived using the effective field theory framework.
2026
Anomalous quartic gauge couplings
Cross-section
EFT
Electroweak
Multiboson
WWgamma
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/400045
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