The existence of right-handed neutrinos with Majorana masses below the electroweak scale could help address the origins of neutrino masses, the matter–antimatter asymmetry, and dark matter. In this paper, leptonic decays of W bosons from 140 fb-1 of 13 TeV proton–proton collisions at the LHC, reconstructed in the ATLAS experiment, are used to search for heavy neutral leptons produced through their mixing with muon or electron neutrinos in a scenario with lepton number violation. The search is conducted using prompt leptonic decay signatures. The considered final states require two same-charge leptons or three leptons, while vetoing three-lepton same-flavour topologies. No significant excess over the expected Standard Model backgrounds is found, leading to constraints on the heavy neutral lepton’s mixing with muon and electron neutrinos for heavy-neutral-lepton masses. The analysis excludes |Ue|2 values above 8×10-5 and |Uμ|2 values above 5.0×10-5 in the full mass range of 8–65 GeV. The strongest constraints are placed on heavy-neutral-lepton masses in the range 15–30 GeV of |Ue|2<1.1×10-5 and |Uμ|2<5×10-6.

Zwalinski, L., Zormpa, O., Zorbas, T.G., Zografos, A., Zoch, K., Zoccoli, A., et al. (2026). Search for heavy neutral leptons in decays of W bosons produced in 13 TeV pp collisions using prompt signatures in the ATLAS detector. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 86(2) [10.1140/epjc/s10052-025-15191-w].

Search for heavy neutral leptons in decays of W bosons produced in 13 TeV pp collisions using prompt signatures in the ATLAS detector

Cerri A.;
2026-01-01

Abstract

The existence of right-handed neutrinos with Majorana masses below the electroweak scale could help address the origins of neutrino masses, the matter–antimatter asymmetry, and dark matter. In this paper, leptonic decays of W bosons from 140 fb-1 of 13 TeV proton–proton collisions at the LHC, reconstructed in the ATLAS experiment, are used to search for heavy neutral leptons produced through their mixing with muon or electron neutrinos in a scenario with lepton number violation. The search is conducted using prompt leptonic decay signatures. The considered final states require two same-charge leptons or three leptons, while vetoing three-lepton same-flavour topologies. No significant excess over the expected Standard Model backgrounds is found, leading to constraints on the heavy neutral lepton’s mixing with muon and electron neutrinos for heavy-neutral-lepton masses. The analysis excludes |Ue|2 values above 8×10-5 and |Uμ|2 values above 5.0×10-5 in the full mass range of 8–65 GeV. The strongest constraints are placed on heavy-neutral-lepton masses in the range 15–30 GeV of |Ue|2<1.1×10-5 and |Uμ|2<5×10-6.
2026
Zwalinski, L., Zormpa, O., Zorbas, T.G., Zografos, A., Zoch, K., Zoccoli, A., et al. (2026). Search for heavy neutral leptons in decays of W bosons produced in 13 TeV pp collisions using prompt signatures in the ATLAS detector. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 86(2) [10.1140/epjc/s10052-025-15191-w].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/1322435